This form of betting is particularly common in rugby, where the bookies try to give the 'weaker' team a head start so that the two teams are level.
For example, if Italy is playing Scotland in a Six Nations match at Murrayfield, the Italians may be 'awarded' a 22 points start on the handicap by the bookmakers. If you felt that Italy had been underestimated and could win the match, or lose by less than 22 points, then you would back them on the handicap.
With a handicap, the odds offered are generally 5/6 on each team, with approximately 14/1 or 16/1 offered on a tie - if Italy beat Scotland by exactly 22 points.
However if you felt sure that the Italians would win the match, you should simply back them on the match betting odds without a handicap. Although this means that you wouldn't get the 22 point start, it does mean that the price would be more attractive. In our example (below), the odds on Italy winning would rise from 5/6 to 9/1 without a handicap.
(Above) Table showing varying prices for an Italy v Scotland match with a 22 point handicap start for Italy (+22).