What is "varchar"

A sweep or variable-length character field is a set of character data of undetermined length. The term sweep refers to a data type of a field (or column) in a database management system. Fields sweep may be of any size, up to the limit set in the specific system.

The limit is different from database types: an Oracle 9i database has a limit of 4,000 bytes, a Mysql database has a limit of 65,535 bytes (shared limit for the entire line) and Microsoft SQL Server 2005 has a limit of 8000 bytes (unless varnish(max) is used, which has a maximum storage capacity of 2 gigabytes).