Question: So there's these villagers (called `TESTIFICATE`?!) inhabiting my villages. Can I interact with them? What happens if I kill them?

Answer: 
Villagers were introduced in the beta 1.9 pre-release, and, for the most part, act like passive mobs: they'll get up in your grill and walk around without a care in the world. When you kill them, they don't drop anything.

In addition, 1.2 brought [a number of changes](http://www.minecraftwiki.net/wiki/1.2) to mob AI such as villagers:

* entering houses at night and leave them in the morning
* breeding to populate all the houses in a village
* enabling the automatic creation of [iron golems](http://www.minecraftwiki.net/wiki/Iron_Golem) that protect them

The first new behavior—entering houses at night and leaving them in the morning—allows you to use villagers as [a poor man's daylight detector](https://imgur.com/a/7FTaS).

Finally, as of [snapshot 12w21a](http://www.mojang.com/2012/05/minecraft-snapshot-week-21/), villagers power Minecraft's economy by trading items with players.
I have Played Minecraft for a few now, but ever since i started, i spawned a Villager Egg. To me it seems they:

At night, they go in any possible Home Nearby,
They are capable of climbing ladders, and walking up stairs
They run away from zombies,enderman, and spiders
Soon, when a new version comes out, they will be able to breed and have kids, that YOU can name.
They mainly eat Cake,but some are different.