I joined lichess.org back in August, it is a really simple looking (function over looks) chess based site with great data. Over time I have been enjoying the site quite a bit and it has an iOS app too. What really stood out to me was how it is totally free and does not place ads all over the place like many sites do littering the net. I have lots of respect for any website that offers so much for our enjoyment while not exploiting the visitors.
Decided to make donation for a lifetime patron badge on my profile out of respect for the site in general. You can learn chess and play online at this site with everything available for free. Go check out the site at lichess.org, note the website version has lots more features than the app currently.