MySQL Describe output explanation

This MySQL table is generated by ActiveRecord.

+--------------------+-------------+------+-----+---------+----------------+
| Field              | Type        | Null | Key | Default | Extra          |
+--------------------+-------------+------+-----+---------+----------------+
| id                 | int(11)     | NO   | PRI | NULL    | auto_increment |
| RecordType         | tinyint(4)  | YES  |     | NULL    |                |
| Location           | varchar(8)  | YES  |     | NULL    |                |

Please explain to me what is meant by tinyint(4) in the second column. According to MyS开发者_StackOverflow社区QL documentation the size of tinyint is one bytes. But does this mean it takes actually 4 bytes to store this data. The code for generating the second column is like this.

t.column :RecordType, :integer, :limit => 1

It means it uses 1 byte for that data type, not 4 so therefore the range of possible numbers is smaller (-128 to 127 or 0 - 255 for unsigned or 2^8 if you will which is 1 byte).

TINYINT(4) is the display length, so it means it'll use four digits to represent the number.