A political alliance, also known as a coalition or bloc, is cooperation by members of different political parties, in countries with a parliamentary system, on a common agenda of some kind. This usually involves formal agreements between two or more entire parties, and often takes place mainly for the purpose of contesting an election. An alliance is usually especially beneficial to the parties concerned during and immediately after elections – due to characteristics of the electoral systems concerned (e.g. allowing each party to clear election thresholds) and/or allowing parties to participate in formation of a government after elections.