Agreement to agree. A mutual understanding between two or more legally competent individuals or entities that they will later enter into a contract even though the contract's exact terms have not yet been decided; non-binding.

Binding agreement. An enforceable agreement or contract.

Collective bargaining agreement. A contract between an employer and a  union or other representative, voluntarily selected by a majority of the employer's workers within a bargaining group, concerning the wages, hours, and other conditions of employment for that group.

Divorce agreement. An agreement between spouses made during a divorce concerning child custody, child and spousal support, property distribution, and other matters. Such agreements are usually incorporated into the parties' divorce decree.

Gentlemen's agreement. An agreement not intended by the parties to be legally enforceable, but that is expected to be performed or followed as a matter of friendship or honor. May or may not involve illegal subject matter such as gambling bets.