I am researching on the topic of scaling, and I discovered something called the middleware which is basically handling the requests, correct? If that is true, what is the middleware in a LAMP stack? It's Apache right? How can I even check what is handling my requests? I want to know more about the LAMP stack and scaling, and have read a lot of questions on SF already, but I don't really know what questions to ask so if anyone can just throw down a megaton of knowledge on me or point me to the right resources, that would be great!
TLDR: I want to learn more about LAMP stack and scaling the LAMP stack but don't know where to begin. I am a total beginner.
Edit:
I also read these:
http://people.apache.org/~sctemme/ApconUS2007/scalingout.pdf
http://people.apache.org/~sctemme/ApconEU2006/FR4/FR4_Performance_Up.pdf