The PHP Team has released End of Life information for PHP 4. There will be no more releases of PHP 4 after December 31, 2007 (the end of this year), and critical security issues will no longer be patched after August 8, 2008.
PHP 4 was initially released on May 22, 2000. PHP 4 was a huge step-up from PHP 3, and people started using it soon after it’s release. PHP 5 was initially released on July 13, 2004. Although PHP 5 offered much more better things than PHP 4, PHP 5 adoption was taken very slowly. Mostly because PHP 4 offered everything people needed, and PHP 5 just improved on those features and added some other stuff that people didn’t really need, but they were useful. Even today, in 2007, PHP 5 is still second to PHP 4.
Hopefully the PHP 4 EOL will start to make people use PHP 5. Let’s face it, PHP 4 obsolete. Hosts have plenty of time to get PHP 5 on their servers, and software writers have lots of time to make sure their software works on PHP 5.
PHP 5 adoption by hosts would go a lot quicker if software starting requiring a minimum of PHP 4. GoPHP5.org is trying to get software writers to make PHP 5.2 a minimum requirement.
We’ve had this discussion on the WordPress WP-Hackers mailing list a couple of times. The majority wants to make PHP 5(.2) a minimum requirement. The “lead developers” haven’t really said much on the discussion, though. Although, by the looks of this post that Matt Mullenweg (founder of WordPress) wrote on his Blog, it doesn’t look like it’ll be happening anytime soon…