PHP (Personal Homepage or Hypertext Preprocessor) is one of the well-known programming languages. It is simple and preferable for many to build a small website and web applications. PHP has a vast community with lots of active members. WordPress, Flickr, and Wikipedia are some websites that are built with PHP. It is the most used server-side programming language by far. Approximately 75 percent of all webpages are powered by PHP.

If you are asking if there is anything special you need to know before you start learning PHP, the answer is no. Just dive in to the PHP: Documentation and get started.

One of the reasons for PHP's success is that it has really great documentation. Every concept is broken down in simple terms and explained fully. And on each page, visitors to the site comment and fill in more examples and missing details.

PHP is also one of the simplest and most straightforward scripting languages. This makes it very easy to learn.

In order to use PHP effectively, you will eventually need to learn other languages, such as:

1. HTML, because it's what PHP normally outputs to the browser

2. MySQL, because you'll want to store user data in a database

3. CSS, because it's how you add style to HTML pages

4. JavaScript, because you'll want to make your HTML pages interactive

I listed those in the order that I recommend you learn them. But I recommend that you start with PHP.