PHP – the server-side programming language powering over 80% of the web – is now at version 7.1. As an interpreted (as opposed to compiled) language, PHP code is executed in run-time meaning there is no slow compilation step – changes you make in the code are visible instantly, and it is this quick feedback loop that allows for PHP’s speed of use.
If you’re just getting started with PHP, here are some introductory materials to get you up to speed.
A guide on how to properly protect your MySQL database from SQL injection attacks by using a little common sense, good programming practices and PHP.
I love it when people say "a simple way to do xyz is to use regular expressions" and then offer what amounts to a string of indecipherable hieroglyphics to answer the question. However, once you know how to leverage the power of regular expressions, they can be very useful tools.