Second building you open. Pretty self-explanatory. This is where your Residents go to eat. Though not its only source, the Kitchen uses a certain amount of food from the Mill. Keep this in mind in the early game and make sure your Mill is producing the maximum amount of food it can.

This building is a main component in keeping your Residents healthy and happy. If they aren't getting the proper nutrition, their mood can drop and they will even get sick. This happened to me. Even though I was being good with setting the Furnace to max during the night and storms and my Houses were all upgraded to their max, my Residents started getting sick. Took me a minute, but I eventually discovered it was because my food quality was too low.

Luckily, there is a menu you can change to increase the quality of food for your Residents. When you tap on your Kitchen, at the bottom you will see a little yellow menu button.