投票 (tóu piào) means 'to vote' in the general sense of casting a ballot in an election or referendum. 选举 (xuǎn jǔ) is specifically 'to elect' someone to a position, while 表决 (biǎo jué) means 'to vote on a particular motion or proposal' in a meeting or committee. Use 投票 when focusing on the act of voting itself.