Proxy Bid:

A Proxy bid is the maximum dollar amount you are willing to bid for a specific lot. The system automatically bids up to that amount on your behalf against competing bidders (if any).

EXAMPLE: You enter a "Max Proxy Bid" amount of $500 when the lot's reserve is met and the high bid is $100.  Your Proxy Bid automatically raises your bid to the next minimum bid amount, which in this example is $125, and thus makes you the current high bidder.  When a competing bidder bids $150, the system again automatically places the next minimum bid amount of $175 for you, making you the high bidder again.  If a competing bidder bids again, proxy bidding continues until your "Max Proxy Bid" of $500 is exceeded by the next minimum bid amount. If your proxy bid amount is not exceeded by the next minimum bid amount when the auction ends, then you win the lot.

ADVANTAGES: Should your schedule prevent you from participating near the closing of an Auction, your "Proxy Bid" quickly bids on your behalf.  Also, when your and a competing bidder's proxy bids are of equal amount ($500 in the example) at the end of the Auction, your bid wins, because you entered your $500 "Proxy Bid" amount first.