Bid

When you go the Auction House, you can buy a wide range of different items that other players have put up for auction (or just look at all the neat gear and items that have been put up). When you choose Bid, you will be able to browse all the different of items that have been put up for sale.

If you want to see more information on an item, just click on the item and a list of options will appear:

Price History
Bid
Sort

Price History
Choosing this option will show you a list of the ten last sales, who sold the item, and who bought it for how much. If you click on a particular entry, it will also show the time of purchase in your chat window.
Bid
This option is only available if someone has put that item up for sale. If you choose this option, you can enter a price that you're willing to pay for the item and enter a bid. If any sellers have put the item up for lower than your bid, you will get it! If not, it will tell you that you were unable to buy it. You can keep bidding higher and higher (but no more than the amount that you have...) if you're willing to. Your sale goes to the person who has their item listed for the lowest amount, or in the event of a tie, the one who listed the item first.
Sort
You can sort the lists of items with this button. For weapons and armor, you are given an option of sorting choices (see below), and for all other items, it will automatically sort them alphabetically. If you click the sort button again, it will reset the list to its original order. A note: if you have your weapon or armor list sorted one way and want to sort it another, reset the list first, then choose the new sort option.
Weapons can be sorted by Damage, by Delay, by Level, by Job, or by Race. Armor can be sorted by Defense, by Resistance, by Level, by Job, or by Race.
This article uses material from the "Bid" article on FFXIclopedia and is licensed under the CC-BY-SA License.