Wandering traders are passive mobs that can spawn randomly around the player at any time. They usually have multiple trade offers which turn out to be either completely useless or sometimes good. In some situations, they might be selling you something which is hard to find or too dangerous to obtain personally. In patch v1.14, Mojang added the wandering trader to the game, and over a few updates, it was given more features.
A trader with a llama (Via Screenshots)
The wandering trader roams around with two llamas and they appear randomly, seemingly out of thin air. Usually, they either spawn in villages or somewhere near the player (within a 48-block radius). The traders have a very complicated spawn cycle, as only one can spawn in a loaded chunk. It is possible to have more traders, but they will be in unloaded chunks. Traders spawn really quickly after the world generation has taken place, usually after one Minecraft day (20 minutes). The spawn rate for the first attempt is 2.5%, but worry not. This number gradually increases after each passing Minecraft day.
If you happen to be on an island the game would still spawn the wandering trader and usually, they show up in the water. If you are mining and are deep enough, traders can also spawn underground. After 40-60 minutes the trader along with his llamas starts to despawn, but there are exceptions to this. If you kill the traders and leave the llamas alone, they don't despawn even if they are in unloaded chunks (only in Bedrock Edition). But there is no way you can stop the trader itself from despawning. Placing him in a boat or giving him a name tag doesn't stop the process.
A trader spawned in a village (Via Screenshots)
A wandering trader walks around villages and around the player and usually has 6 trades to offer. These trades are completely random and you can sometimes obtain a rare item if you are able to fulfill the trade requirements. There are limits to how many times you can trade the same item, as after the wandering trader has run out of an item in stock, the trade will get locked. If all the trades have been locked, the trader despawns faster.
If the trader and his llamas are spotted by other llamas, they may form a caravan and follow the leashed llamas. The traders carry milk and invisibility potions with them at all times. They use the invisibility potion at dusk to stay safe from the monsters, and milk is used to remove the effects of the potion at dawn. They like to keep their distance from all types of zombies, and unlike villagers, they don't turn into zombie villagers. The trader is passive and doesn't attack when provoked by the player; instead, they run away, but their llamas proceed to spit on any aggressors, players, and mobs alike.
Wandering Traders have a mechanic where players can exchange emeralds with the trader for items in return. Interacting with the Wandering Trader allows you to see what items are for sale, similar to villagers. Wandering Traders sell generated items or nature-related items such as dyes, seeds, etc. Sometimes, you will get trades for biome-specific items, this offers you a way to obtain such items without traveling all the way to the biomes themselves. There is a limit to how many times you can purchase an item, as after a couple of repeated purchases the trader will lock the trade.
Unlike villagers who unlock their trades after a while, the Wandering Trader does not. If you manage to lock all the trades, the Wandering Trader will despawn much quicker than normal, but new ones will spawn with different offers. Even if attacked by the player, the Wandering Trader will not change the price of the items being sold. They don't change the prices based on demand and don't have an experience bar. Also, you cannot sell items to them. An important thing to remember is that the Wandering Trader cannot restock items, so use them wisely.
The trading menu (Via Screenshots)
When killed, the Wandering Traders drop no experience. But you can get a milk bucket, a potion of invisibility, and leads from killing the trader. There is an 8.5% chance of you receiving the bucket of milk if the trader is killed while they are holding it, or before they finish drinking it. The same goes for the invisibility potion. This chance is increased by the level of looting on your weapon, 1% per level to be precise. Once killed, the leads between the trader and their llamas disconnect and fall to the ground.
The Wandering Trader was inspired by the traveling merchants in other prominent RPGs such as Runescape. Unlike villagers, Wandering Traders won't turn into zombies when attacked by them. Also, they won't turn into witches when struck by lightning.
The Wandering Trader is a passive mob that can bring you sweet deals from time to time. Try to maximize the benefits you can gain from them. Killing them can get you 2 leads which can be quite handy if you have animal farms or a horse.
A. To tame the llamas, you need to keep mounting them until they settle down. They will kick you off the first couple of times.
A. No, they are designed to be transient, unlike normal villagers. They despawn after a while and a new one will spawn in.
A. Wandering traders spawn nearby players and villages. It takes them about three and a half hours to spawn after the world has been generated.
A. No, wandering traders will eventually despawn even if you have placed them in a boat or named them with a name tag.