Pokémon Eggs

Eggs can be obtained from PokèStops around the world, then you can select them from the Poké Menu -> Pokémon -> the tab Eggs. Here you can see how many Kilometres (KM) you need to walk to open them.

Kilometers walked appear to be positively correlated to the CP of the hatched Pokémon.

Once you selected the egg you want to open, select your incubator and then you can go back to play, your Kilometres will be registered while you play, once you walk enough you will be warned about the opening.

There are two types of Incubators, one (received at the beginning of the game) is for unlimited use and the others are for 3 times use.

List of receivable Pokémon
Eggs have been observed to come in three types, based on the distance you must walk for them to fully incubate: 2 KM, 5 KM, 10 KM