A legal expression for a situation where a party has acted or carried out a duty or task or obligation in a sincere manner. Generally speaking, in human interactions, good faith is a sincere intention to be honest, fair, and open, irrespective of the outcome of such an interaction.

In contract law, it is the implied covenant of honest and fair dealing that is assumed to be exhibited and undertaken by the parties to a contract. The parties show intent to deal with each other honestly and fairly so as to not undermine or negatively affect the right of the other party or parties to receive the benefits associated with, or resulting from, the contract. Good faith is implied in contracts in order to reinforce the outright covenants or promises of the parties towards complete execution/ performance in accordance with terms and conditions set out in the contract.

Good faith is also known in Latin as bona fides.