"Sniping" is a user-coined description for placing a last minute, sometimes last second, bid on an auction.

The rule on eBay is that any bid placed before the auction ends is "fair game".

There is a way to avoid the frustration of being outbid at the last minute while the item price is still within your spending limit. Simply bid the absolute maximum amout that you are willing to pay and let our proxy system do the work of increasing your bid only when someone has outbid you.

By placing your bid as outlined above, a "sniper" will only be able to outbid you only if they are truly willing to spend more for the item than you are. If they place a last-second bid that isn't high enough, they will generally not have enough time to get back in and place another bid before the auction ends.