PHP is basically an Open source, Server-Side language (Similar to Java, Dot-net, Python in general) having
It has it's own pros & cons.
It's easy to learn.
Even a non-computer knowledge can learn easily with minimul effort.
Most of the Application in market are using it because of its open source.
Latest version of PHP is 7.X (which is most improved version after 5.X).
We have soo many built-in functions to solve the problem without need to creating custom function(very rarely we do).
Along with PHP we use MySQL (database for storing data) which is also open-source from Oracle.
PHP can be easily integrated with front-end languages like HTML.