Klondike Solitaire is the most popular version of Solitaire, according to About.com. This is the version of Solitaire that comes pre-installed on many PCs. Some other popular Solitaire games are Pyramid Solitaire, Canfield Solitaire, Golf Solitaire and Yukon Solitaire.
Poker Solitaire, Baker's Dozen Solitaire and Good Measure Solitaire are some other popular versions. The last two on About.com's top 10 list are Little Spider Solitaire and Accordion Solitaire.
Canfield Solitaire is similar to Klondike Solitaire. In fact, Klondike Solitaire is often mistakenly called Canfield. In Pyramid Solitaire, players create a 28-card pyramid and try to remove all of the cards from that pyramid by removing two-card combinations that add up to 13. In Golf Solitaire, the goal is to get the lowest score possible.