Villager Professions are the "jobs" that villagers can acquire by finding a compatible workstation. This page will walk you through the steps of adding one yourself.

POI Type (= Point of Interest Type) is an object that determines detectable blocks in the game. It is used by bees to find their nests, but also by villagers to find a workstation. Adding one is simple as that:

Directory: addon/<namespace>/poi_types/<name>.json
Resulting ID: <namespace>:<name>

{
  "block": "minecraft:redstone_lamp"
}

You can also add "max_tickets" and "valid_range" settings, but they will fallback to 1 which is the usual values for villager workstations. So a simple json like that is enough.

To let Minecraft know that our new POI type is suitable for villagers, we need to add it to minecraft:acquirable_job_site tag. Simply add a file as following:
Directory: data/minecraft/tags/point_of_interest_type/acquirable_job_site.json

{
  "values": [
    "test:redstone_lamp"
  ]
}

test:redstone_lamp is supposed to replaced with the ID of your POI type of course.

Adding the actual profession is also very easy:

Directory: addon/<namespace>/villager_professions/<name>.json
Resulting ID: <namespace>:<name>

{
  "poi_type": "test:redstone_lamp",
  "sound_event": "minecraft:entity.villager.work_librarian"
}

poi_type must be the ID of your newly made POI type!

A villager profession needs two texture: One for the normal villager, and one for the zombified villager. The texture locations are:
assets/<namespace>/textures/entity/villager/profession/<name>.png
assets/<namespace>/textures/entity/zombie_villager/profession/<name>.png
You can use MC's textures as a template.

You can also decide how the model for the villager hat will be like if you provide a mcmeta file like this next to the texture: Directory: assets/<namespace>/textures/entity/villager/profession/<name>.png.mcmeta

{
    "villager": {
        "hat": "full"
    }
}

The hat setting can either be none, partial or full. This file is however not needed.

Click here to the files from the example pack.