HUDS in video games are overlays which give information. There are three types of HUDS, permanent HUD, a hud which is always on,an example of this could be a health bar. Pull-up HUD,this is determined by the user, for example you can hide your chat. Finally the action HUD, this is a hud that used when the user triggers it, for example your screen going red when loosing health.
On my moodboard i have many different examples of different HUDS in game, for the first image(7 days to die), you can see an item box, and different percentages of health food, and other things you need to stay alive, these are permanent HUDS. However if you look at the image below(4story Global), where it shows a leaderboard, that is a pull up HUD as the user can hide it when he/she wants to. However this image also has permanent HUDS, such as the skill bars, the Experience bar and the health bars. Finally, an example of an action HUD, in COD 4. As the player is being damaged this causes a red screen to come up, the more hurt the player is the more red the screen gets. Another example of an action HUD is the ‘+10’ score that comes up on screen, this action is only triggered when the player gets a kill or captures an objective.