Politics and policy-making in modern democracies imply the search for compromises. In doing so, members of parliament with similar policy positions can form short-term coalitions to increase the chances that their law proposals are supported by a majority in the legislature. While the latter behavior of parliamentary representatives can often be observed in presidential systems, the government in parliamentary systems needs the support of a majority in the legislature, either to get into or to remain in office. In order to win stable majorities in parliaments over a longer time period, the parliamentary groups of political parties can either form legislative coalitions that agree on specific policy goals, so that a minority government is supported by a parliamentary majority, or they form executive coalitions where the coalition parties are also represented in the government and, thus, additionally have to agree on the distribution of ministerial posts.
