I was on Wikipedia reading about web application frameworks. They don't show any pictures or video so I don't fully understand. Is using a web application framework like Cake the best way to learn PHP? I want to eventually learn to code a web site as complicated as Twitter. Were sites like Twitter and Facebook made using a web application framework? I have a hunch the answer is no. These sites were custom made from the ground up. Thanks.
I wouldn't recommend learning PHP with the cake framework. It's a good MVC framework, but will probably slow your learning. If you want to do MVC style coding, you don't necessarily need to use a framework, PHP has the capability for this kind of thing built in (see this page for a working example of that). To answer your other question, no, other most other big sites don't use frameworks. Don't worry about the bigger sites though. Get 100 users and scale to their needs. Don't worry about a million users if you don't have them.
You should check the sticky in this subforum http://forums.digitalpoint.com/showthread.php?t=1483351 Sites like Facebook and Twitter have custom frameworks, like the one Invision Power Services made for their board. Also, my recommendation is to check the Zend Framework, they have many good solutions (Zend_Form for example) that you could implement in your own framework (if you decide to make one).
I dont want to say which framework is better coz I know each one has its own advantages.. Just want to answer your question, if you just started to learn php, I dont think using framework will help you.. You can start using frameworks once you've mastered the basics of php, mysql and javascript eventually.
I would say its best to know the basics of PHP first (functions, data types, operations, etc) before starting off with a framework. Frameworks for the most part tend to try to make larger tasks done faster or easier, but they're merely a crutch that can take just as long to use if you don't understand the Basics.
Thank you all for your advice and thanks for the links too. I think I will stay away from any frame work for the time and just learn to program.