When your HP drops to 0, you don’t die immediately. You’ll still have a chance to run away and perform an emergency heal to yourself. This won’t heal that much so you still have to quickly use a bandage or adrenaline shot.
When you die by any means, you’ll have two options: wait for someone to revive you or use a pacemaker. The latter is considered a premium item so you can’t rely on it. If there’s another player nearby, he/she can revive you before the timer expires. You can also do the same to other players on the verge of death.
If there’s no one around, you can choose to give up. This will take you back to a random starting location in the map. If you’re in a Pact Zone (PvE), you’ll be transported to a safe area (cabin in Fall Forest, Cave in Sand Castle, etc). However in PvPvE areas, you’ll be taken to a random starting location.
When you die, a marker of the spot where you died will be displayed in the map. You’ll lose a portion of your backpack’s contents, your gear’s durability will be reduced, and you’ll be really hungry. In PvE areas, you can backtrack to this death marker and recover your lost items. You can also see other players’ death markers though you can’t pick up their items.
In PvP areas, your dropped backpack can be looted by enemy players so don’t be surprised (or expect) if your death marker has disappeared in the map. In this mode however, you can pick up other player’s items by finding their death markers, regardless if you killed them or not.
The exception for these are deaths in special areas like the Trap Infection instance. When you die, you don’t lose anything and your gear’s durability won’t be decreased. You’ll also get automatically revived. However, your HP and hunger meters won’t be full when you get revived so you still have to eat up and heal up.