Asp.net confused question

Hi  Dear 
1.i  am too much confused that About page init,Page prerender and page render plz Explain  Not post link
2. What is Application pooling.
3.  what is web garden how we used in webconfig.
4.    what is  difference b/w session and cache.
Plz do not post link  Plz explain briefly...
 
 
 
 
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