C# Language Specification

Keywords

A keyword is an identifier-like sequence of characters that is reserved, and cannot be used as an identifier except when prefaced by the @ character.

keyword: one of
abstract as base bool break
byte case catch char checked
class const continue decimal default
delegate do double else enum
event explicit extern false finally
fixed float for foreach goto
if implicit in int interface
internal is lock long namespace
new null object operator out
override params private protected public
readonly ref return sbyte sealed
short sizeof stackalloc static string
struct switch this throw true
try typeof uint ulong unchecked
unsafe ushort using virtual void
volatile while

In some places in the grammar, specific identifiers have special meaning, but are not keywords. Such identifiers are sometimes referred to as “contextual keywords”. For example, within a property declaration, the “get” and “set” identifiers have special meaning (§10.7.2). An identifier other than get or set is never permitted in these locations, so this use does not conflict with a use of these words as identifiers. In other cases, such as with the identifier “var” in implicitly typed local variable declarations (§8.5.1), a contectual keyword can conflict with declared names. In such cases, the declared name takes precedence over the use of the identifier as a contextual keyword.

4.