Election threshold

In party list systems, an election threshold is an absolute limit of support (as a fraction of the number of votes cast) below which a party obtains no seats.

Election thresholds are often used to keep minor parties from becoming kingmakers and exercising too much power that way. However, too high thresholds can reduce party competition.

In some party systems with multiple procedures, the threshold might only apply to one procedure. For instance, the electoral threshold in Norway only applies to the distribution of top-up leveling seats, and parties retain their county seats even if they fall short of the threshold.

Background
As of April 2022, English Wikipedia describes the "election threshold" the following way:

The electoral threshold, or election threshold, is the minimum share of the primary vote which a candidate or political party requires to achieve before they become entitled to any representation in a legislature. This limit can operate in various ways, e.g. in party-list proportional representation systems where an electoral threshold requires that a party must receive a specified minimum percentage of votes (e.g. 5%), either nationally or in a particular electoral district, to obtain any seats in the legislature. In multi-member constituencies using preferential voting, besides the electoral threshold, to be awarded a seat, a candidate is also required to achieve a quota, either on the primary vote or after distribution of preferences, which depends on the number of members to be returned from a constituency.

The effect of an electoral threshold is to deny representation to small parties or to force them into coalitions, with the presumption of rendering the election system more stable by keeping out fringe parties. Proponents say that simply having a few seats in a legislature can significantly boost the profile of a fringe party and that providing representation and possibly veto power for a party that receives only 1% of the vote not be appropriate; however, critics posit that in the absence of a ranked ballot system, supporters of minor parties are effectively disenfranchised and denied the right of representation by someone of their choosing.

Two boundaries can be defined—a threshold of representation is the minimum vote share that might yield a party a seat under the most favorable circumstances for the party, while the threshold of exclusion is the maximum vote share that could be insufficient to yield a seat under the least favorable circumstances. Lijphart suggested calculating the informal threshold as the mean of these.