By Mike Hills
From well-rehearsed zingers to off-the-cuff comebacks, the debate answers that provoked a reaction.
The former vice-president came under attack for his record on immigration when in the White House.
Challenged by more moderate contenders, Senator Elizabeth Warren questioned what motivates their bids.
When challenged on the details of his healthcare plan, Medicare for All, the Vermont senator shot back.
There were tense exchanges - and moments of agreement - on the debate stage in Miami.
There were policy disagreements, interruptions and some unexpected lines on the debate stage in Miami.