The Nether
The Nether is an extremely dangerous place. There are mobs in the Nether that can be found no where else. But there are many hostile mobs.

The Nether has a lot of lava and cliffs. There are many ways you could die, if you are not prepared.
Bastion Remnants and Nether Fortresses spawn in the Nether.
Bastion Remnants have piglins and piglin brutes that spawn there. Each Bastion Remnant has a chest, unless it is cut off. The chests will have special items, but don't let a piglin see you open it. They will attack you.
Nether Fortresses are made of Nether Brick. Blazes and wither skeletons spawn there. It has chests too. No mobs will attack you, but all the mobs in the Nether Fortresses are hostile, so it doesn't matter.
Notes and tips:
- If you see gold in the netherack (basically what the whole Nether is made of), only mine it if there is no piglins around. They will attack you. (This only counts for piglins. Zombified piglins are fine.)
- Wear gold armour, any piece is fine (we recommend boots). Piglins like gold and won't attack you if you are wearing one. You can trade with them too.
- Make a trail of torches to help guide you, on your way back.
- Use a sword and shield to fight mobs, but also keep a stack of arrows and a bow.
- Use a hopper to collect the items in the chests (in Bastion Remnants and Nether Fortresses).
- Use a strider to cross big pools of lava.
- Make sure your portal will not get destroyed (which makes it so you cannot get back) by Ghast fireballs.
- Make some type of landmark to mark where your portal is.
- Make a base (something to hide behind, and doesn't burn) when fighting Ghasts and Blazes.
- Always make sure you have extra armour and shields, and lots of food.