Crafting is used to create unique items with different materials, that couldn't be obtained otherwise.
To access the crafting window, press Start > Features > Crafting.
Everyone starts on crafting level 1. You can increase your level by crafting various recipes and thus increasing your EXP. You can see how much EXP you need to the next level in the title bar of the crafting window.
Increasing your crafting level may unlock some recipes automatically or make certain recipes from Drops or NPCs learnable.
At level 60, you may choose a crafting path at the Mighty Manager. There are currently 2 crafting paths:
Being a crafter increases your experience gained from crafting by 30%. Some recipes may also yield some additional items when crafting.
Gatherers are able to see and collect materials throughout the world that crafters can't, but will need in the later stages of the game.
There are also some recipes only craftable by gatherers.