Health

Health is a property of Humanoid objects that determines the current vitality of that Humanoid. Whenever Health drops to 0, the Humanoid dies and the Died event fires.

Health GUI
ROBLOX's Health GUI is a bar representing a player's character's current Health (the size of the green or red bar) and MaxHealth (the size of the current Health bar is determined in proportion of MaxHealth). The Health GUI is placed near the center of the bottom of the Player's screen. The standard Health GUI can be edited and even removed by Scripts and LocalScripts.

History
Since the beginning of ROBLOX, ROBLOX had a hard-coded GUI for the health bar, as in one which could not be modified by the user. Then, as of the introduction to the LUA-GUI, the current Health GUI now appears instead. At first, the Health Bar was on the right side of the screen, which is a green bar that turns red when health lowers. Also, blue text saying "Health" is under it. In the 2nd version, it was made bigger. In the 3rd version, it changed completely, it is now on the bottom and white text saying "Health" is inside it. Also, when a large amount of health is reduced, the Health Bar flashes red, when the player's health was low, the health bar turned red. A notable change is what looks like blood when the player dies instantly or loses a large amount of health appears on the corners of the screen. On the 4th and current version, the health bar no longer blinks when a large amount of health is lost, also, the text font changed.

Trivia

 * In game, when Health drops to 0 in anyways except falling from baseplate, there will be a "uhh" sound.
 * It is speculated that the death sound may change to an audio called "Boredfrankly 2013" by user EchoDuplication.
 * When a Humanoid being thrown at high speed then the Health drops to 0, the death sound becomes more low-pitched or high-pitched depending on how fast the humanoid is being thrown.
 * The "ooh" sound made by ROBLOXians is similar to the "ooh" damage sound made by players in early versions of Minecraft.