Breeding

Requirements
Most Villager tech requires many villagers to properly function, and Villagers do not naturally re-spawn in the world. Therefore, Breeding Villagers is an important field to understand in order to create many Villagers to use for your various contraptions.
Villagers have 3 requirements to breed baby Villagers:
Outfits
Villagers can have different outfits depending on what Biome they were born in. When a baby Villager is born the outfit it dawns will be determined by the biome, and there is no association with the outfits the parents currently wear. As an example, if a Savanna Villager and a Desert Villager breed in a Tundra, a Tundra baby Villager will be born. 
Knowing what biome(s) is linked to each outfit allows you to know where to find or create Villagers of a specific type. This is useful because outfits can determine certain trades offers. See Buying and Selling Resources for more info.
There are 7 types of outfits a Villager can have:
Possible Outfits
Associated Biomes
Desert
 Badlands
Desert
Eroded Badlands
Wooded Badlands
Savanna
 Savanna
 Savanna Plateau
 Windswept Savanna
Taiga
 Old Growth Pine Taiga
 Old Growth Spruce Taiga
 Taiga
 Windswept Hills
 Windswept Forest
 Windswept Gravelly Hills
Snow
 Deep Frozen Ocean
 Frozen Ocean
 Frozen Peaks
 Frozen River
 Grove
 Ice Spikes
 Jagged Peaks
 Snowy Beach
 Snowy Plains
 Snowy Slopes
 Snowy Taiga
Jungle
 Bamboo Jungle
 Jungle
 Sparse Jungle
Swamp
 Mangrove Swamp
 Swamp
Plains
 Meadow
 Plains
 Sunflower Plains
All Other Biomes
Note: Biomes in Bold denote that a Village naturally generates there