Supported PHP Versions
Although I do my best to accommodate everyone, I have had to make the stance only to support PHP 7.1+. If you run a site with a PHP version older than this I highly recommend you upgrade to at least PHP 7.1. Older versions of PHP are no longer supported and may contain security issues.
PHP 5.5+
How to determine your version of PHP
This is a handy plugin that will display your PHP version on WordPress Admin dashboard:
WordPress’s view
As stated on WordPress.org’s requirements page, WordPress recommend that WordPress is run on a server that supports PHP 7.4+.