What is your favorite website.?

I was wondering waht your favorite website was. One THAT IS APPROPRIATE.!!!!! I would like a website that I can play on while I am home. But please make sure it is appropriate. For anyone under the age of 15.! My little sibling might want to play. Ooo and can you please explain what the website is too.:))) PLEASE AND THANK YOU TOO ALL WHO HELP ME;)