Guide
Mahjong Solitaire vs. Mahjong
People often use “mahjong” to mean the tile-matching puzzle you play alone in a browser. That is actually mahjong solitaire - a different game that just borrows the tiles. Here is the difference in one minute.
Mahjong - the four-player game
Traditional mahjong is a social game for four players that grew up in 19th-century China. On your turn you draw and discard tiles, racing to complete a hand of sets and pairs - a bit like rummy with gorgeous tiles. There is strategy, reading opponents, scoring, and a good deal of luck. A game needs other people (or bots) and a scorepad.
Mahjong solitaire - the tile-matching puzzle
Mahjong solitaire is a single-player puzzle invented for computers in the 1980s. The 144 tiles are stacked into a shape (the classic one is the “turtle”), and you clear them by removing matching pairs of free tiles. No hands, no discarding, no opponents - just you and the board. It became one of the most-played computer games in the world, and it is what most browser “mahjong” games actually are.
Same tiles, different game
The tiles are the only thing they truly share: three suits, winds and dragons, and the flower and season bonus tiles (explained here). Everything else - the goal, the rules, the number of players - is different. If you have only ever played the browser puzzle, you have played mahjong solitaire, not mahjong.