Spider Solitaire can be played at the AARP website by going to http://games.aarp.org/games/spider-solitaire.aspx and then clicking "Play Now." It's also possible to type "spider solitaire" into the search box on the site and be directed to the game.
Spider Solitaire is considered the king of solitaire games. In this game, the player removes cards from ten columns by creating a sequence from King to Ace of the same suit in a single column. A stack of cards or a single card of the same suit and in sequence can be moved. Once a column is empty, any stack or single card can be moved to that column. The game has been won once all cards are cleared.
There are a number of other types of solitaire games that can be played on the AARP site. They can be found by using the search box or clicking on the games section.