Solo, sometimes known as Solo Whist, is a trick-taking card game based on whist. A major distinctive feature is that one player often plays against the other three.

Play proceeds as for whist. The cards may be dealt singly, or in threes, with a single card for the last round. The dealer's last card is turned up and left exposed for one round of play, whether used for trumps or not. One deal constitutes a game.

After the deal, the game starts with a round of bidding in which players may make the following declarations, listed here in ascending order of value:

1. Proposal (aka prop) - declarer invites another player to join in a pairing that will make eight tricks
2. Acceptance (aka cop) - declarer agrees to proposal
3. Solo - declarer will alone make five tricks
4. Misère - declarer will make no tricks - no trumps
5. Abondance (abundance) - declarer will choose trumps and alone make nine tricks
6. Abondance with trumps determined by the turn-up card (Royal abundance)
7. Misère ouverte - declarer will make no tricks, with no trumps and with his cards open to the other three after the first trick
8. Abondance declarée (abundance declared); - declarer will choose trumps and alone make thirteen tricks
9. Abondance royale declarée (Royal abundance declared); with trumps determined by the turn-up card

Bidding starts with the player on the dealer's left. A player may only make a declaration of more value than any previous declarations. Bidding continues until all players pass.

Betting: stakes may be agreed for each declaration category, and for over- and undertricks. There are no over- or undertricks in contracts for misère, misère ouverte, or abundance declared.