Introduction
PHP Prime is a framework built for the clients of Code Poets.
I would not recommend that anyone creates a framework of their own. I have one because it existed before most frameworks (since 2003), and I find that it gives me a more advanced base to work with.
I should point out that this framework is not supported for anyone else, however you may find some of the ideas different to some of the typical frameworks, for example:
Security, Accessibility, and Performance are key elements.
SQL is preferred over an ORM, as you need to know what the database is doing if you want to improve performance and be aware of security.
Objects are used to avoid code duplication, but procedural code is used in units to avoid too many abstractions (easier to read and understand what is going on).
The system is self testing (as the page loads), where it will complain if anything is wrong. This is a slightly different approach to normal TDD, where tests are separate.
Debug mode provides considerable amounts of help, such as reminding you about key features, showing the processing time, and checking/displaying the SQL.
It is very strict, e.g. using "application/xhtml+xml" in development (ensuring correct HTML nesting), and applying a limited CSP header (e.g. no inline JS).
Next steps
At least scan over the notes on security, which applies to all websites.
Then setup your project.