A framework is a skeleton that we can use for sofware development. Using a framework will help us use standard and robust patterns in our application, making it more stable and well known by other developers. PHP has many different frameworks you can use in your daily work. We will see some standards used on the most common frameworks so that you can pick the best for your project.
For years, the PHP community has been working on their own projects and following their own rules. Thousands of different projects with different developers have been released since the first years of PHP, and none followed any common standards.
This was a problem for PHP developers, firstly because there was no way of knowing if the steps they were following to build applications were the correct ones. Only their own experience and the Internet could help the developer guess if their code was written properly and if it would be readable by other developers in the future.
Secondly...