Have you used frameworks? What are the benefits of using them over general PHP?

CodeIgniter and CakePHP are both nice.

You basically use a framework because they keep you from having to start from scratch each time you do a project. You get a lot of nice features like form validation, templating, and an MVC architecture without having to do much work.

For super-simple projects, they may not be worth it. And for really unique, complex projects, they may not be suitable. But for your generic CRUD app, a nice framework can save you a lot of time.

Personally, I use the Zend Framework for most of my works. Unlike some other frameworks, all its modules can be used separately while still being very integrated.

The reason why you should use a framework is what upstarter said.