Tokens allow you to add textual information to token text fields. You can insert tokens into a field using the Insert Token popup near the field or by choosing Insert Token from the Edit menu. You can also start typing a token and use type completion to complete the token.
The available tokens are listed on the wiki Tokens page.
Text token fields also process %NN% or %NNNN% as arbitrary hex unicode characters (eg %41% is an A), and (except for regular expression fields) process backslashed characters \a,\b,\e,\f,\t,\r,\n (bell,backspace,escape,form feed,tab,return,line feed).
To include a percent in your text, simply double the percent (%%). To include a backslash in your text, double the backslash (\\).