A running mate is a person running together with another person on a joint ticket during an election. The term is most often used in reference to the person in the subordinate position (such as the vice presidential candidate running with a presidential candidate) but can also properly be used when referring to both candidates.
Running mates may be chosen, by custom or by law, to balance the ticket geographically, ideologically, or personally; examples of such a custom for each of the criteria are, geographically, in Nigerian general elections, in which a presidential candidate from the predominantly Christian south is typically matched with a vice presidential candidate from the predominantly Muslim north, and vice versa, ideologically, the Brazilian general elections in 2010 and 2014, where Dilma Rousseff of the left-wing Workers' Party ran alongside Michel Temer of the center-right Brazilian Democratic Movement Party, and, personally, the 2016 Bulgarian presidential election, in which both candidates who went on to the second round of voting, Rumen Radev and Tsetska Tsacheva, had running mates of the opposite gender. The objective is to create a more widespread appeal for the ticket and the results can range from assisting the resulting pair of candidates in appealing to a larger base of people to deterring voters who were initially inclined to vote for the running candidate, but may have been put off by the choice of the running mate.