Minecraft/HUD

Minecraft has a Heads-Up Display (HUD) visible on the screen. It can be toggled on and off through certain keybinds or game settings.

Hotbar
At the bottom of the screen is the hotbar. This contains 9 items in your inventory, including the item you are currently holding (outlined in white).

Crosshair
The crosshair is a small + in the middle of the screen. It shows the exact point where the character is facing.

Status bars

 * The hearts represents HP and deplete when you take damage. If it drops to zero you die and respawn at the last bed you slept in, or where you first entered the world if you have not slept in a bed or the bed was destroyed. Half a heart is worth 1 HP.
 * The green bar is the XP bar. This bar shows how much XP you have gained since leveling up. Your current level is displayed in a green number. The XP levels are used in enchanting. You lose all your levels if you die, but some levels are dropped as EXP where you died. EXP can be gained by mining, smelting, and killing mobs, among other things.
 * The meat pieces are your hunger bar. The hunger bar goes down by being active. If your hunger bar is full enough,your HP will automatically be restored. If your hunger bar drops enough, you will be unable to sprint. If your hunger bar runs out you steadily lose HP. Eat food to restore your hunger bar and health. Any food (but not potions or water) restore hunger, although some foods (in particular raw chicken, rotten flesh, and pufferfish) have negative side effects.
 * The gray shirts represent your armor if you wear it. Armor reduces the damage you take from enemies. However, it does not reduce all damage. Armor can also break.
 * If you are underwater, the HUD will have bubbles. The bubbles disappear if underwater for prolonged periods of time. If all of the bubbles disappear, you will lose health.

Chat
If you are in a multiplayer world then chat messages from other players appear on the left side of the screen.