What is the purpose of circumcision?

I will answer it personally, i think for me if it is circumcised, it looks better than not. And when you are cleaning it, you can clean it more better as i am very particular with the smell,because i myself is very particular with personal hygiene.

as far as i know when there is possibility of build up of smegma,which is y most of them go for circumcision.

Circumcision was first used to protect men against infection and/or irritation due to dirt or sand getting underneath the foreskin. Circumcision continues to have something religious and cultural for people around the world, but whether or not it still offers health benefits is an issue currently under much debate.

because it is more sanitary there are instances of infection from not cleaning properly around the extra skin

The idea behind circumcision is that, this increases the hygiene. What they say is once this is done, the genital won't have accumulated dust, or other dirt, so it would remain clean and the chance of infection is lower. I asked my muslim friend about that now, he told me this.

Personally i think it is asthetic more these days than for any other reason. In today's world, it is simple to keep it clean. It isn't medically necessary anymore but a lot of people do it because it is expected. It's one of those "you're different" kind of things.