What is a middle in sports betting?

A middle is when you bet both sides of a game at different lines, hoping the final score falls between them so both bets win. For example, betting Team A -2.5 early and then Team B +4.5 after the line moves. If Team A wins by 3 or 4, both bets cash. If neither hits the middle, you typically lose only the vig — one bet wins, one loses.