Snakes and Ladders was originally an Indian game, Moksha-Patamu, which also served as a metaphor for Hindu ethics. Landing on a square labelled with a virtue would cause the piece to advance, while landing on a square containing a vice would send the piece back.
Virtuous squares were at the bottoms of ladders; if you land here, you automatically go up the ladder to the square on top. Vice squares have the heads of snakes on them; if you land here, you automatically go down the snake's body to the square at the bottom.
Original boards have a 100-square grid, numbered in a back-and-forth manner: so that square #1 is in the lower left-hand corner, and square #100 (the winning square) is in the upper left-hand corner. The top and bottom rows have 14 squares, all the rest have 12. There are 8 rows.
Virtue: Faith (12), Reliability (51), Generosity (57), Knowledge (76), and Asceticism (78).
Vice: Disobedience (41), Vanity (44), Vulgarity (49), Theft (52), Lying (58), Drunkenness (62), Debt (69), Murder (73), Rage (84), Greed (92), Pride (95), and Lust (99).
All players start at square #1. A die is rolled to determine movement. (In most variants, players who roll 6 get another turn.) Whoever reaches square #100 first wins.
The placement of the snakes and ladders differs from set to set. Western versions have an equal number of snakes and ladders. The game and toy company Hasbro owns the copyright to a variant, Chutes and Ladders.