What was an Elector, as in the Elector of Saxony?

The Electorate of Saxony, was a territory of the Holy Roman Empire from 1356 to 1806 that wa initially centred on Wittenberg that but later included the cities of Dresden, Leipzig and Chemnitz and their surrounds. In the Golden Bull (Decree) of 1356, Emperor Charles IV declared the Duchy of Saxe-Wittenberg an electorate, which meant a territory whose ruler was one of the prince-electors who chose the Holy Roman emperor.

https://en.wikipedia.org/wiki/Electorate_of_Saxony

Interesting because I was watching an
episode of the old TV series The Wild Wild West in which Artemus Gordon pretended he was the Elector of Saxony.
The Series took place during the administration of President Grant.