Hi, I have experience in PHP for 3 years, and I think these are advantages pf PHP:
Open source: It is developed and maintained by a large group of PHP developers, this will helps in creating a support community, abundant extension library.
Speed: It is relative fast since it uses much system resource.
Easy to use: It uses C like syntax, so for those who are familiar with C, it’s very easy for them to pick up and it is very easy to create website scripts.
Stable: Since it is maintained by many developers, so when bugs are found, it can be quickly fixed.
Powerful library support: You can easily find functional modules you need such as PDF, Graph etc.
Built-in database connection modules: You can connect to database easily using PHP, since many websites are data/content driven, so we will use database frequently, this will largely reduce the development time of web apps.
Can be run on many platforms, including Windows, Linux and Mac, it’s easy for users to find hosting service providers.