% (Wildcard - Character(s) to Match) (Transact-SQL)
SQL Server 2005
Matches any string of zero or more characters. This wildcard character can be used as either a prefix or a suffix. For more information, see Pattern Matching in Search Conditions.
Transact-SQL Syntax Conventions
Reference
LIKE (Transact-SQL)Operators (Transact-SQL)
Expressions (Transact-SQL)