What do I need to know before buying RAM?

[Apoorv Srivastava]

I need 8 gb DDR3 ram but i find that there are some around 8000 INR and some around 5000 INR. What is the difference and which one should I go for?

 

[kapitalistas]

http://www.tomshardware.com/faq/id-1722156/ram-guide.html this one helps credit goes to author.