Ask.fm is an FAQ about you. The purpose of the social site is to setup a profile and have visitors ask you questions that you publicly answer.
So why is this different that Twitter or any other social network? Honestly I think it’s just like Twitter, but more like the old MySpace. The social profiles are one dimensional and they only have one function, let people ask you questions and you answer them. You can connect Ask.fm to your twitter as an extension which I noticed many are doing.
Give Ask.fm a try, I think you will enjoy it. However as always, you need to be careful about what you post online and keep your digital footprint secure.