An optional character (or string of characters) used to delimit substrings within the input string. It can be a numeric or string literal (enclosed in single quotation marks), the name of a variable, or an expression that evaluates to a string.
Commonly, a delimiter is a designated character which is never used within string data, but is set aside solely for use as a delimiter separating substrings. A delimiter can also be a multi-character string, the individual characters of which can be used within string data. If you specify no delimiter, the default delimiter is the comma (,) character.