Dear Abhijith,

If you fall into any category, you are among the lucky ones! The benefit of being a OBC, SBC, SC, ST or NT student is that the cutoffs to get into colleges is lower than general category students. Also your rank plays an important role. I'll explain you with an example. Suppose you want to get into IIT BOMBAY, then the cutoff  rank for general category is 60 (Comp. Sci) and that for OBC is 44(Comps. Sci). Here the obc rank is rank given to all obc candidates according to their marks and such canditates are less than general category so getting a seat becomes easier. Other categories like SC,ST  have even lower cutoffs and even such students are less in number. So it is of great use. 

Hope this helps.

All the best!