Static and Dynamic table in mysql

http://dev.mysql.com/doc/mysql/en/Static_format.html
http://dev.mysql.com/doc/mysql/en/Dynamic_format.html

Static format is the default for MyISAM tables. It is used when the table contains no variable-length columns (VARCHAR, BLOB, or TEXT). Each row is stored using a fixed number of bytes.

Dynamic storage format is used if a MyISAM table contains any variable-length columns (VARCHAR, BLOB, or TEXT), or if the table was created with the ROW_FORMAT=DYNAMIC option.