With an autobid, the system automatically bids for you. You specify a maximum bid and the system automatically bids with you until your maximum bid is outbid. For example, do you want to bid a maximum of 20 euros on a lot? Then the system keeps track of the bids and automatically places a higher bid for you if you are outbid. The system stops outbidding when the 20 euros is reached. Handy right?
Note: if you are the highest bidder on a lot and you set an autobid, you will outbid yourself. The system will give you a warning and ask if you are sure you want to place the bid. Have you placed a bid? Then you can't cancel it.