string
From ISV Support Wiki
String
Field Type string includes free form text as well as specific formats such as currency, numbers, decimal numbers, percentage, phone numbers, URL, and email.
In Formula Fields, text strings are enclosed in single 'quotes'.
Example Text Strings
235 Maple Ave. Joe Johnson Flower Mound, Texas telephone: 408-555-1212 $29.95 fred@abcxyz.com www.mywebpage.com 07/24/2010 37.6% 0.234664