How does bidding work on a listing with a reserve price?
Once you place a bid, eBay will compare your bid against the seller's reserve price. If your maximum bid is below the reserve price, eBay will raise the current bid on the item to your maximum bid. At this point you have not met the reserve price, and are not obligated to purchase the item. You will be asked if you want to bid again.

If your bid is above the reserve price, eBay will raise the current bid to the same amount as the reserve price. Your maximum bid is then saved in case someone bids against you. If another bid is placed that is still below your maximum bid, eBay will automatically raise your current bid just enough to ensure you remain as the high bidder. If another bid is placed that exceeds your maximum bid, you will no longer be the high bidder, and you will be asked if you would like to bid again.

Note: You can always raise your maximum bid, regardless of whether you are the high bidder.

Examples

The seller's reserve price is: $10,000

Suppose you bid $8,000. Your bid will appear on the item listing page as $8,000. The reserve price has not yet been met. You must bid again if you are still interested.

Now you bid $11,000. Your bid will appear on the item listing page as $10,000. Congratulations, you are the current high bidder and the reserve price has been met.

How does bidding work on a "no reserve" listing?
Once you place a bid, eBay will compare your bid to other bids on the item. If your bid is above the highest maximum bid, eBay will raise your current bid just enough to ensure that you become the high bidder. Your maximum bid is saved in case someone else bids against you. If another bid is placed that is still below your maximum bid, eBay will automatically raise your current bid just enough to ensure you remain as the high bidder. If another bid is placed that exceeds your maximum bid, you will no longer be the high bidder, and you will be asked if you would like to bid again. You can always raise your maximum bid, regardless of whether you are the high bidder.

If you place a bid that is below the highest maximum bid on the item you will be told you are not the high bidder and you'll be asked to bid again.

Examples

Starting bid is $100. Another bidder has a hidden maximum bid of $1,000

Suppose you bid $600. The current bid on the item listing page will become $610. Thank you for your bid, but another bidder has a higher maximum bid. Please bid again if you are still interested.