Timestamp From Online Manual
A timestamp is a way of representing times in programming languages. Usually, this is a unix timestamp, expressed as the number of seconds since midnight on December 31, 1969. As an example, the timestamp of January 1, 2006 at 12:00:00 am is 1136102400.
In MySQL, you can easily work with this by using the UNIX_TIMESTAMP() and FROM_UNIXTIME() functions, which translate between dates as strings and dates as timestamps. Examples include:
SELECT UNIX_TIMESTAMP('2006-01-01 0:00:00'); SELECT FROM_UNIXTIME(1136102400); INSERT INTO smf_members (memberName, realName, emailAddress, dateRegistered, passwd) VALUES ('member', 'member', 'firstname.lastname@example.org', UNIX_TIMESTAMP(NOW()), MD5('password'));
In PHP, you can work with them by using the time(), strftime(), and strtotime() functions.