iPad sim card?

Could be up there as one of my greatest ‘dumb questions’ but…

I won a ipad and it is asking for a sim card.
As it’s not a phone, why?
What do I put in there and what do I need a sim card for? SMS?

for data charges…
you can get away without one, if you connect to a WiFi network for your downloading.

Ok, that’s what I am doing currently.

It’s a micro sim so you can connect to 3G data networks.