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# Aliasing
The `type` statement can be used to give a new name to an existing type. Types
must have `UpperCamelCase` names, or the compiler will raise a warning. The
exception to this rule are the primitive types: `usize`, `f32`, etc.
```rust,editable
// `NanoSecond`, `Inch`, and `U64` are new names for `u64`.
type NanoSecond = u64;
type Inch = u64;
type U64 = u64;
fn main() {
// `NanoSecond` = `Inch` = `U64` = `u64`.
let nanoseconds: NanoSecond = 5 as U64;
let inches: Inch = 2 as U64;
// Note that type aliases *don't* provide any extra type safety, because
// aliases are *not* new types
println!("{} nanoseconds + {} inches = {} unit?",
nanoseconds,
inches,
nanoseconds + inches);
}
```
The main use of aliases is to reduce boilerplate; for example the `IoResult<T>` type
is an alias for the `Result<T, IoError>` type.
### See also:
[Attributes](../attribute.md)
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