Santa?

My son will be 11 this December. I believe when i was this age maybe younger, i seen my mom sneaking the red, gold and silver presents out. Those were the colors santa wrapped his presents in. Thats how i found out about who the real santa.

Now i know there is a real Santa that helped people.

Anyway i asked my son the other day if he knows who santa is. Of course he brought up red fat man with magic. I was hoping maybe he already knew, maybe his father told him. My question is when and how did you explain who santa is? What age did/will tell your children?