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diff --git a/browser/components/urlbar/docs/nontechnical-overview.rst b/browser/components/urlbar/docs/nontechnical-overview.rst new file mode 100644 index 0000000000..e3fb6d7600 --- /dev/null +++ b/browser/components/urlbar/docs/nontechnical-overview.rst @@ -0,0 +1,628 @@ +Nontechnical Overview +===================== + +This document provides a high level, nontechnical overview of Firefox's address +bar, with a focus on the different types of results it shows and how it chooses +them. + +.. contents:: + :depth: 2 + + +Terminology +----------- + +This document uses a small number of terms of art that would be helpful to +understand up front. + +Input + The text box component of the address bar. In contrast, we use "address bar" + to refer to the whole system comprising the input, the view, and the logic + that determines the results that are shown in the view based on the text in + the input. + +Result + An individual item that is shown in the view. There are many different types + of results, including bookmarks, history, open tabs, and search suggestions. + +View + The panel that opens below the input when the input is focused. It contains + the results. + +Maximum Result Count +-------------------- + +The view shows a maximum of 10 results by default. This number is controlled by +a hidden preference, ``browser.urlbar.maxRichResults``. + +Search Strings +-------------- + +If the user has not modified the text in the input or the text in the input is +empty, we say that the user's **search string** is empty, or in other words, +there is no search string. In contrast, when the user has modified the text in +the input and the text is non-empty, then the search string is that non-empty +text. + +.. figure:: assets/nontechnical-overview/empty-url.png + :alt: Image of the address bar input showing a URL + :scale: 50% + :align: center + + Empty search string: The input text has not been modified + +.. figure:: assets/nontechnical-overview/empty-placeholder.png + :alt: Image of the address bar input showing its placeholder text + :scale: 50% + :align: center + + Empty search string: The input text is empty (and the input is showing its + placeholder text) + +.. figure:: assets/nontechnical-overview/non-empty.png + :alt: Image of the address bar input showing "porcupines" text + :scale: 50% + :align: center + + Non-empty search string: The input text has been modified and is non-empty + +The distinction between empty and non-empty search strings is helpful to +understand for the following sections. + +Top Sites +--------- + +When the search string is empty and the user focuses the input, the view opens +and shows the user's top sites. They are the same top sites that appear on the +new-tab page except their number is capped to the maximum number of address bar +results (10). If the user has fewer top sites than the maximum number of results +(as is the case in a new profile), then only that number of results is shown. + +.. figure:: assets/nontechnical-overview/top-sites.png + :alt: Image of the address bar view showing top sites + :scale: 50% + :align: center + + Top sites on a new en-US profile + +This behavior can be turned off by going to about:preferences#privacy and +unchecking “Shortcuts” in the “Address Bar” section. In that case, the view +closes when the search string is empty. + +Searches +-------- + +When the search string is non-empty, the address bar performs a search and +displays the matching results in the view. Multiple separate searches of +different sources are actually performed, and the results from each source are +combined, sorted, and capped to the maximum result count to display the final +list of results. In address bar terminology, each source is called a +**provider**. + +Each provider produces one or more types of results based on the search +string. The most common result types include the following (not exhaustive): + +.. figure:: assets/nontechnical-overview/search-suggestion.png + :alt: Image of a search suggestion result with text "porcupine meatballs" + :scale: 50% + :align: center + + Search suggestions from the user's default engine (magnifying glass icon) + +.. figure:: assets/nontechnical-overview/form-history.png + :alt: Image of a previous search result with text "porcupines" + :scale: 50% + :align: center + + Previous searches the user has performed from the address bar and search bar + (clock icon) + +.. figure:: assets/nontechnical-overview/bookmark.png + :alt: Image of a bookmark result with text "Porcupine - Wikipedia" + :scale: 50% + :align: center + + Bookmarks + +.. figure:: assets/nontechnical-overview/history.png + :alt: Image of a history result with text "Porcupines | National Geographic" + :scale: 50% + :align: center + + History + +.. figure:: assets/nontechnical-overview/open-tab.png + :alt: Image of an open tab result with text "Porcupines | San Diego Zoo + Animals & Plants" + :scale: 50% + :align: center + + Open tabs (switch to tab) + +.. figure:: assets/nontechnical-overview/remote-tab.png + :alt: Image of a remote tab result with text "Porcupine | rodent | + Britannica" + :scale: 50% + :align: center + + Remote tabs (via Sync) + +How the address bar combines and sorts results from different providers is +discussed below in `Result Composition`_. + +The Heuristic Result +-------------------- + +The first result in the view is special and is called the **heuristic** +result. As the user types each character in their search string, the heuristic +result is updated and automatically selected, and its purpose is to show the +user what will happen when they press the enter key without first selecting a +(non-heuristic) result. The heuristic result is so called because it shows +Firefox's best guess for what the user is trying to do based on their search +string. + +The heuristic result is determined by running through a number of different +heuristics and picking the one that first matches the search string. The most +important heuristics in the order that Firefox runs through them are: + +*Is the search string...* + +1. An omnibox extension keyword? Extensions using the omnibox API can register + keywords by which they become activated. +2. A bookmark keyword? The user can associate a keyword with each bookmark. + Typing a bookmark keyword plus an optional search string and pressing enter + will visit the bookmark. + + .. figure:: assets/nontechnical-overview/bookmark-keyword.png + :alt: Image of the address bar input with text "bug 1677126" and a + bookmark keyword heuristic result + :scale: 50% + :align: center + + Typing "bug" triggers a Bugzilla bookmark with the keyword "bug" + +3. A domain name or URL that should be autofilled? **Autofill** is the name of + the feature where the input completes the domain names and URLs of bookmarks + and frequently visited sites as the user is typing them. (Firefox autofills + “to the next slash”, meaning it first autofills domain names and then partial + paths.) + + .. figure:: assets/nontechnical-overview/autofill.png + :alt: Image of the address bar input with text "mozilla.org/" with + "illa.org/" selected and an autofill heuristic result + :scale: 50% + :align: center + + After typing "moz", the rest of mozilla.org is automatically completed + +4. A valid URL? If so, visit the URL. (This includes fixing common typos like + “mozilla..org” and “mozilla.ogr”. Valid URLs are based on the `Public Suffix + List`_. The user can also specify an allow-list using hidden preferences to + support domains like localhost.) + + .. figure:: assets/nontechnical-overview/visit.png + :alt: Image of the address bar input with text "porcupine-fancy.org" and a + visit heuristic result + :scale: 50% + :align: center + + Typing a URL that isn't bookmarked or in history + + .. _Public Suffix List: https://publicsuffix.org/ + +5. Ultimately fall back to performing a search using the default engine. (The + user can opt out of this fallback by setting the hidden preference + ``keyword.enabled`` to false. In that case, Firefox stops at the previous + step and attempts to visit the user's search string as if it were a URL.) + + .. figure:: assets/nontechnical-overview/search-heuristic.png + :alt: Image of the address bar input with text "porcupines" and a search + heuristic result + :scale: 50% + :align: center + + Typing a string that will perform a search using the default engine + +Result Composition +------------------ + +For a given search string, the address bar performs multiple separate searches +of different providers and then combines their results to display the final +list. The way in which results are combined and sorted is called **result +composition**. Result composition is based on the concept of result groups, one +group after another, with different types of results in each group. + +The default result composition is described next, starting with the first +result. + +1. Heuristic Result +~~~~~~~~~~~~~~~~~~~ + +The first result is always the heuristic result. + +2. Extension Omnibox Results +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The next group of results is those provided by extensions using the omnibox +API. Most users never encounter these results because they are provided only by +extensions that use this feature, and even then the user must type certain +extension-defined keywords to trigger them. There are at most 6 results in this +group. + +3. Search Suggestions +~~~~~~~~~~~~~~~~~~~~~ + +The next group is search suggestions. Typically this group contains 6 results, +but the exact number depends on certain factors described later in `Result +Composition Nuances`_. There are actually three types of search suggestions: + +* Previous searches the user has performed from the address bar and search bar + (denoted with a clock icon): + + .. image:: assets/nontechnical-overview/form-history.png + :alt: Image of a previous search result with text "porcupines" + :scale: 50% + :align: center + + This is the only type of search suggestion that is generated by Firefox alone, + without the help of a search engine. When the user performs a search using an + engine from the address bar or search bar (and only the address bar and search + bar), Firefox stores the search string, and then when the user starts to type + it again, Firefox includes it as a result to make it easy to perform past + searches. (Firefox does not store search strings used within web pages like + google.com.) + +* Suggestions from the user's default engine (denoted with a magnifying glass + icon): + + .. image:: assets/nontechnical-overview/search-suggestion.png + :alt: Image of a search suggestion result with text "porcupine meatballs" + :scale: 50% + :align: center + + These are fetched from the engine if the engine provides the necessary access + point. The ordering and total number of these suggestions is determined by the + engine. + +* Google-specific "tail" suggestions, which look like "... foo" and are provided + for long and/or specific queries to help the user narrow their search: + + .. image:: assets/nontechnical-overview/tail-suggestions.png + :alt: Image of a tail suggestion results with text "porcupine abc def" in + the input and two suggestions with text "... definition " and + "... defense" + :scale: 50% + :align: center + + These are fetched from Google when Google is the user's default engine. The + ordering and total number of these suggestions is determined by Google. + +The search suggestions group typically contains two previous searches followed +by four engine suggestions, but the exact numbers depend on the number of +matching previous searches and engine suggestions. Previous searches are limited +in number so that they don’t dominate this group, allowing remote suggestions to +provide content discovery benefits. Tail suggestions are shown only when there +are no other suggestions. + +The user can opt out of showing search suggestions in the address bar by +visiting about:preferences#search and unchecking "Provide search suggestions" or +"Show search suggestions in address bar results". + +4. General Results +~~~~~~~~~~~~~~~~~~ + +The final group of results is a general group that includes the following types: + +* Bookmarks +* History +* Open tabs (switch to tab) +* Remote tabs (via Sync) +* Sponsored and Firefox Suggest results (part of the Firefox Suggest feature) + +This general group is labeled "Firefox Suggest" in the Firefox Suggest feature. + +Typically this group contains 3 results, but as with search suggestions, the +exact number depends on certain factors (see `Result Composition Nuances`_). + +Most results within this group are first matched against the search string on +their titles and URLs and then sorted by a metric called **frecency**, a +combination of how frequently and how recently a page is visited. The top three +results are shown regardless of their specific types. + +This is the only group that is sorted by frecency. + +A few important complexities of this group are discussed in the next +subsections. The final subsection describes frecency in more detail. + +Adaptive History +................ + +The first few bookmark and history results in the general group may come from +**adaptive history**, a system that associates specific user search strings with +URLs. (It's also known as **input history**.) When the user types a search +string and picks a result, Firefox stores a database record that associates the +string with the result's URL. When the user types the string or a part of it +again, Firefox will try to show the URL they picked last time. This allows +Firefox to adapt to a user's habit of visiting certain pages via specific search +strings. + +This mechanism is mostly independent of frecency. URLs in the adaptive history +database have their own sorting score based on how many times they have been +used in the past. The score decays daily so that infrequently used search +strings and URLs aren't retained forever. (If two adaptive history results have +the same score, they are secondarily sorted by frecency.) + +Within the general group, the number of adaptive history results is not limited, +but typically there aren't many of them for a given search string. + +Open and Remote Tabs +.................... + +Unlike bookmarks and history, open and remote tabs don't have a "natural" +frecency, meaning a frecency that's updated in response to user actions as +described below in Frecency_. Tabs that match the search string are assigned +constant frecencies so they can participate in the sorting within the general +group. Open tabs are assigned a frecency of 1000, and remote tabs are assigned a +frecency of 1001. Picking appropriate frecencies is a bit of an art, but Firefox +has used these values for some time. + +Sponsored and Firefox Suggest Results +..................................... + +Sponsored and Firefox Suggest results are an exception within this group. They +are matched on predetermined keywords, and when present, they always appear last +in the general group. Frecency isn't involved at all. + +Frecency +........ + +Frecency is a complex topic on its own, but in summary, each URL stored in +Firefox's internal history database has a numeric score, the frecency, +associated with it. Larger numbers mean higher frecencies, and URLs with higher +frecencies are more likely to be surfaced to the user via the address bar. Each +time the user visits a URL, Firefox increases its frecency by a certain "boost" +amount that depends on how the visit is performed -- whether the user picked it +in the address bar, clicked its link on a page, clicked it in the history +sidebar, etc. In order to prevent frecencies from growing unbounded and to +penalize URLs that haven't been visited in a while, Firefox decays the +frecencies of all URLs over time. + +For details on frecency, see `The Frecency Algorithm`_. + +.. _The Frecency Algorithm: https://docs.google.com/document/d/10LRRXVGWWWcjEZIZ2YlEmuKkQqh2RaTclStFHNnPqQ8/edit#heading=h.588hanspexub + +Preferences that Affect Result Composition +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +There are a number of options in about:preferences that affect result +composition. + +The user can opt out of showing search suggestions in the address bar by +unchecking "Provide search suggestions" or "Show search suggestions in address +bar results" in about:preferences#search. (The first checkbox applies to both +the address bar and search bar, so it acts as a global toggle.) + +.. figure:: assets/nontechnical-overview/prefs-show-suggestions.png + :alt: Image of the preferences UI that allows the user to opt out of search + suggestions + :scale: 50% + :align: center + + Preferences allowing the user to opt out of search suggestions + +By default, the search suggestions group is shown before the general results +group, but unchecking "Show search suggestions ahead of browsing history in +address bar results" in about:preferences#search does the opposite. In that +case, typically the general results group will contain at most 6 results and the +search suggestions group will contain at most 3. In other words, regardless of +which group comes first, typically the first will contain 6 results and the +second will contain 3. + +.. figure:: assets/nontechnical-overview/prefs-suggestions-first.png + :alt: Image of the preferences UI that allows the user to choose whether + search suggestions are shown before general results + :scale: 50% + :align: center + + Preference allowing the user to choose which group is shown first + +The “Address Bar” section in about:preferences#privacy has several checkboxes +that allow for finer control over the types of results that appear in the view. +The top sites feature can be turned off by unchecking “Shortcuts” in this +section. + +.. figure:: assets/nontechnical-overview/prefs-privacy.png + :alt: Image of the preferences UI that allows the user to choose which + results are shown + :scale: 50% + :align: center + + Preferences allowing the user to choose which results are shown + +Result Composition Nuances +-------------------------- + +Among the search suggestions and general results groups, the group that's shown +first typically contains 6 results and the other group contains 3 results. The +exact number in each group depends on several factors: + +* The total maximum result count (controlled by the + ``browser.urlbar.maxRichResults`` hidden preference). + + The total number of results in the two groups scales up and down to + accommodate this number so that the view is always full of results. + +* The number of extension results. + + The extension results group comes before both groups, so if there are any + extension results, there are fewer available slots for search suggestions and + general results. + +* The number of matching results. + + The search string may match only one or two search suggestions or general + results, for example. + +* The number of results in the other group. + + The first group will try to contain 6 results and the second will try to + contain 3, but if either one is unable to fill up, then the other group will + be allowed to grow to make up the difference. + +Other Result Types +------------------ + +The most common result types are discussed above. This section walks through the +other types. + +An important trait these types have in common is that they do not belong to any +group. Most of them appear at specific positions within the view. + +Search Interventions +~~~~~~~~~~~~~~~~~~~~ + +Search interventions help the user perform a task based on their search string. +There are three kinds of interventions, and each is triggered by typing a +certain set of phrases_ in the input. They always appear as the second result, +after the heuristic result. + +The three kinds of interventions are: + +.. figure:: assets/nontechnical-overview/intervention-clear.png + :alt: Image of the clear intervention result with text "Clear your cache, + cookies, history and more" + :scale: 50% + :align: center + + Clear history, cache, and other data search intervention + +.. figure:: assets/nontechnical-overview/intervention-refresh.png + :alt: Image of the refresh intervention result with text "Restore default + settings and remove old add-ons for optimal performance" + :scale: 50% + :align: center + + Refresh Firefox search intervention + +.. figure:: assets/nontechnical-overview/intervention-update.png + :alt: Image of the update intervention result with text "The latest Firefox + is downloaded and ready to install" + :scale: 50% + :align: center + + Update Firefox search intervention + +Currently this feature is limited to English-speaking locales, but work is +ongoing to build a more sophisticated intent-matching platform to support other +locales, more complex search strings, and more kinds of interventions. + +.. _phrases: https://searchfox.org/mozilla-central/rev/c4d682be93f090e99d5f4049ceb7b6b6c03d0632/browser/components/urlbar/UrlbarProviderInterventions.jsm#64 + +Search Tips +~~~~~~~~~~~ + +Search tips inform the user they can perform searches directly from the +address bar. There are two kinds of search tips: + +.. figure:: assets/nontechnical-overview/search-tip-onboard.png + :alt: Image of the onboarding search tip with text "Type less, find more: + Search Google right from your address bar" + :scale: 50% + :align: center + + Onboarding search tip: Appears on the new-tab page + +.. figure:: assets/nontechnical-overview/search-tip-redirect.png + :alt: Image of the redirect search tip with text "Start your search in the + address bar to see suggestions from Google and your browsing history" + :scale: 50% + :align: center + + Redirect search tip: Appears on the home page of the user's default engine + (only for Google, Bing, and DuckDuckGo) + +In each case, the view automatically opens and shows the tip even if the user is +not interacting with the address bar. Each tip is shown at most four times, and +the user can stop them from appearing altogether by interacting with the address +bar or clicking the "Okay, Got It" button. + +Tab to Search +~~~~~~~~~~~~~ + +Tab to search allows the user to press the tab key to enter `search mode`_ while +typing the domain name of a search engine. There are two kinds of tab-to-search +results, and they always appear as the second result: + +.. figure:: assets/nontechnical-overview/tab-to-search-onboard.png + :alt: Image of the tab-to-search result with text "Search with Google" + :scale: 50% + :align: center + + Onboarding tab to search + +.. figure:: assets/nontechnical-overview/tab-to-search-regular.png + :alt: Image of the tab-to-search result with text "Search with Google" + :scale: 50% + :align: center + + Regular tab to search + +The onboarding type is shown until the user has interacted with it three times +over a period of at least 15 minutes, and after that the regular type is shown. + +Search Engine Offers +~~~~~~~~~~~~~~~~~~~~ + +Typing a single “@” shows a list of search engines. Selecting an engine enters +`search mode`_. + +.. figure:: assets/nontechnical-overview/search-offers.png + :alt: Image of the view showing search offer results + :scale: 50% + :align: center + + Search engine offers after typing “@” + +.. figure:: assets/nontechnical-overview/search-offers-selected.png + :alt: Image of the view showing search offer results with one selected + :scale: 50% + :align: center + + After pressing the down arrow key to select Google + +Search Mode +----------- + +**Search mode** is a feature that transforms the address bar into a search-only +access point for a particular engine. During search mode, search suggestions are +the only results shown in the view, and for that reason its result composition +differs from the usual composition. + +.. figure:: assets/nontechnical-overview/search-mode.png + :alt: Image of the view showing search mode + :scale: 50% + :align: center + + Search mode with Google as the selected engine + +Firefox shows suggestions in search mode even when the user has otherwise opted +out of them. Our rationale is that by entering search mode, the user has taken +an action that overrides their usual opt out. This allows the user to opt out +generally but opt back in at specific times. + +Search mode is an effective replacement for the legacy search bar and may +provide a good path forward for deprecating it. + +The user can enter search mode in many ways: + +* Picking a search shortcut button at the bottom of the view +* Typing an engine's keyword (which can be set in about:preferences#search, and + built-in engines have default keywords) +* Typing a single "?" followed by a space (to enter search mode with the default + engine) +* Typing a single "@" to list all engines and then picking one +* If the search bar is not also shown, pressing Ctrl+K (to enter search mode + with the default engine) + +To exit search mode, the user can backspace over the engine chiclet or click its +close button. |