Basic concepts about Output Buffers Control and HTTP Headers
Telerik Software Academy: http://academy.telerik.com/school-academy/meetings/details/2011/10/11/php-school-academy-meeting
The website and all video materials are in Bulgarian.
This lecture discusses the following topics:
Output buffer control
Redirecting the browser
Clipping is a handy way to collect important slides you want to go back to later.