The KEYWORD package contains symbols, called keywords_1,
that are typically used as special markers in programs
and their associated data expressions_1.
Symbol tokens that start with a package marker
are parsed by the Lisp reader as symbols
in the KEYWORD package; see Symbols as Tokens.
This makes it notationally convenient to use keywords
when communicating between programs in different packages.
For example, the mechanism for passing keyword parameters in a call uses
keywords_1 to name the corresponding arguments;
see Ordinary Lambda Lists.
Symbols in the KEYWORD package are, by definition, of type keyword.