The Elder Scrolls: Fate of Tamriel
From p. 150 of Fate Core
A contest proceeds in a series of exchanges. In an exchange, every participant gets to make one skill roll to determine how well they do in that leg of the contest. This is basically an overcome action.
From p. 159 of Fate Core
Exchanges in a conflict are a little more complicated than contests. In an exchange, every character gets a turn to take an action. GMs, you get to go once for every NPC you control in the conflict.
Most of the time, you’re going to be attacking another character or creating an advantage on your turn, because that’s the point of a conflict – take your opponent out, or set things up to make it easier to take your opponent out.