The HUD, or Heads-Up Display, consists of all the on-screen indicators used to indicate the status of you, your party, and the game that are generally shown at most times during gameplay. On-screen at all times, the HUD is one of the primary components of the GUI.
Active Target (1): Displays the name, level and HP of your current target.
Online Status, Minimap and Clock (2): Status indicator showing current delay/connection speeds to the server. The Minimap shows your current position and direction as well as nearby Players, NPCs, monsters and more. Clock shows current game time and day.
Shortcuts Bar (3): Top row are buttons used to interact with other players including trade, party invites, browsing their bazaar or looking at their character information. The bottom row contains quick links
Target Type Filter (4): Shows what target types are used when cycling through targets
Experience Bar (5): Shows the current level and experience points for your active job/class
Action Bar (7): Contains the Actions in use on your active class as well as any custom macros you create.
General Log Window(8): Keeps track of battle messages
Battle Log Window (9): Keeps track of chat and game messages.
Quest Progress window (10): Shows the leve currently active guildleve and your current progress
Targeting Reticule (11): Appears over your current target to distinguish it from other mobs/objects nearby.
Party Status (Above #3, not shown above): Shows the status of party members.
Each HUD can be moved and in some cases, resized to suit your needs. In the configuration menu, there is an option to reset the HUD to default.