Strategic voting, also called tactical voting, sophisticated voting or insincere voting, occurs in voting systems when a voter votes for another candidate or party than their sincere preference to prevent an undesirable outcome. For example, in a simple plurality election, a voter might gain a better outcome by voting for a less preferred but more generally popular candidate. Gibbard's theorem shows that all single-winner voting methods encourage strategic voting, unless there are only two options or dictatorial (i.e., a distinguished agent exists who can impose the outcome). For multi-winner elections no general theorem for strategic voting exists. Strategic voting, even under proportional representation systems, is observed due to non-proportionality, electoral thresholds and quotas. But in systems that use ranked voting, there is no need for strategic voting, and under STV it is impractical to engage in strategic voting. Types of strategic voting (sometimes "useful vote") A voter insincerely ranks an alternative higher in the hope of getting that candidate elected. For example, in the first-past-the-post election, voters may vote for an option they perceive as having a greater chance of winning vs. an option they prefer (e.g., voting for an uncontroversial moderate candidate over a controversial extremist candidate to help defeat a popular candidate of an opposing party). Duverger's law argues that, for this reason, first-past-the-post election methods lead to two-party systems in most cases. In those proportional representation methods that include a minimum percentage of votes that a party must achieve to receive any seats, people might vote tactically for a minor party to prevent it from dropping below that percentage (which would make the votes that candidate does receive useless for the larger political camp that party belongs to), or alternatively, those who support the viewpoints of a minor party may vote for the larger party whose views are closest to those of the minor party. A voter insincerely ranks an alternative lower in the hopes of defeating it. For example, in the Borda count or in a Condorcet method, a voter may insincerely rank a perceived strong alternative last in order to help their preferred alternative win. A voter ranks a perceived weak alternative above their preferred candidate, in order to actually elect the preferred candidate and not the weak candidate. For some electoral systems, a voter may actually elect their preferred candidate by voting for the weak candidate instead. This primarily occurs in runoff voting, when