It's usually used to prevent caching from older caching systems. Fun fact: this specific value of Expires is the birthday of Sasha Schumann, the person who add

It's usually used to prevent caching from older caching systems. Fun fact: this specific value of Expires is the birthday of Sasha Schumann, the person who added this code to PHP[1][2]. [1]: https://stackoverflow.com/a/8194500/2805120 https://stackoverflow.com/a/8194500/2805120 [2]: https://github.com/php/php-src/blob/master/ext/session/session.c#L1221 https://github.com/php/php-src/blob/master/ext/session/sessi...