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+Perform a bitwise operation between multiple keys (containing string values) and
+store the result in the destination key.
+
+The `BITOP` command supports four bitwise operations: **AND**, **OR**, **XOR**
+and **NOT**, thus the valid forms to call the command are:
+
+- `BITOP AND destkey srckey1 srckey2 srckey3 ... srckeyN`
+- `BITOP OR destkey srckey1 srckey2 srckey3 ... srckeyN`
+- `BITOP XOR destkey srckey1 srckey2 srckey3 ... srckeyN`
+- `BITOP NOT destkey srckey`
+
+As you can see **NOT** is special as it only takes an input key, because it
+performs inversion of bits so it only makes sense as an unary operator.
+
+The result of the operation is always stored at `destkey`.
+
+## Handling of strings with different lengths
+
+When an operation is performed between strings having different lengths, all the
+strings shorter than the longest string in the set are treated as if they were
+zero-padded up to the length of the longest string.
+
+The same holds true for non-existent keys, that are considered as a stream of
+zero bytes up to the length of the longest string.
+
+@return
+
+@integer-reply
+
+The size of the string stored in the destination key, that is equal to the size
+of the longest input string.
+
+@examples
+
+```cli
+SET key1 "foobar"
+SET key2 "abcdef"
+BITOP AND dest key1 key2
+GET dest
+```
+
+## Pattern: real time metrics using bitmaps
+
+`BITOP` is a good complement to the pattern documented in the `BITCOUNT` command
+documentation. Different bitmaps can be combined in order to obtain a target
+bitmap where the population counting operation is performed.
+
+See the article called "[Fast easy realtime metrics using Redis
+bitmaps][hbgc212fermurb]" for a interesting use cases.
+
+[hbgc212fermurb]:
+  http://blog.getspool.com/2011/11/29/fast-easy-realtime-metrics-using-redis-bitmaps
+
+## Performance considerations
+
+`BITOP` is a potentially slow command as it runs in O(N) time. Care should be
+taken when running it against long input strings.
+
+For real-time metrics and statistics involving large inputs a good approach is
+to use a replica (with read-only option disabled) where the bit-wise operations
+are performed to avoid blocking the master instance.