In order to pass legislation, the government (the party with the most seats) must persuade some of the members of other parties to vote along with it. If there were two parties with several common goals or ideals, they might form a longstanding coalition. If such a coalition cannot be formed, the ruling party must attract enough votes for pieces of legislation on a case-by-case basis, usually by promising to pass a law desired by the coalition partners or providing some other benefit.

The “fluidity” of the coalitions refers to the fact that they are not static, but constantly changing.