Happiness

Happiness is a basic stat that helps boost most other stats such as beakers, hammers, and growth.

Base for happiness is the basic biomes around you, averaged... So if you choose a very happy spot with lots of flowers lets say, you will get a big boost in your happiness.

The full biome list and bonuses are here at the biomes page.

Several buildings will also boost your happines.

And some events may lower your happiness such as declaring war.