Pokémon Eggs

Pokémon Eggs are Pokémon-related resources which provide Trainers to obtain Pokémon in the other way, than catching them in the wild. They can be obtained from PokéStops around the world. Each owned egg contains random Pokémon and can be hatched by walking one of three specified distances.

Kinds of Pokémon Eggs
Since the release of the game, there were three kinds of Pokémon Eggs, depending how much distance is required to be walked with an egg in incubator in order to hatch it. There are following kinds of eggs:
 * 2-km Eggs,
 * 5-km Eggs
 * and 10-km Eggs.

With the release of the game, all three kinds of eggs had the same, in-game appearance - cream-white egg with pale-green spots on it. After October, 2016, with the release of update to the version 0.43.3, 5- and 10-km Eggs gained different appearance, as their spots became orange and dark-purple respectively.

Pokémon Eggs collection
They can be selected from the Main Menu → Pokémon → Eggs tab.

Players can see currently owned eggs in the Eggs tab under the same in-game interface location, that Pokémon collection and battle parties are.

Hatching Pokémon Eggs
To hatch an egg, a trainer needs to select an incubator, then the desired egg.

There are three types of incubators. An orange one is received at the beginning of the game and has unlimited uses. Others are blue and can be used only three times. The last one is purple and may be used three times, the walking distance for eggs are halved.

Gameplay can carry on as usual when hatching an egg. Kilometers will be registered while the player moves with the app open. Distance is measured by GPS distance, not by movement or number of steps. Once the required distanced has been walked, the egg will appear on the screen with the message "Oh?". Tapping the screen will break the egg open, revealing what is inside.

The Pokémon Go app has limits on speed (approximately 24km/h (15 MPH)). If a person exceeds these limits, the app will not register the distance traveled.

When the app is open, it pings the player's location every 4 minutes. It appears to measure the straight-line distance between pings and will add that distance to every incubator.

Pokémon Eggs hatchlings
There is specified group of Pokémon that trainer can hatch from eggs. This group of Pokémon changes with new Pokémon being added to the game or temporally for the certain events. Pokémon hatched from eggs always come with a respective amount of their specified candy well.

The CP of Pokémon hatched from eggs is based on the trainer's level when the egg was acquired, not when it is hatched.

Changes
From the date of release of the game until now, there were several changes to distances and Pokémon that could be hatched from eggs.

Trivia

 * After game release, there were disputes in player community, whether or not region-exclusive Pokémon could be hatched from eggs that were obtained from PokéStops outside the regions, that such Pokémon spawn is.
 * Niantic has confirmed region-exclusive Pokémon, by that time: Mr. Mime, Tauros, Kangaskhan and Farfetch'd, could only be hatched from eggs obtained in the designated region.
 * Sometime later in summer 2016, all 4 region-exclusive Pokémon were permanently removed from eggs, and since that time there have been no more any regional Pokémon in eggs.
 * All Pokémon possible to be hatched from eggs are the first-stage evolution forms of their Pokémon families.
 * Hatching Pokémon Eggs is the only way to obtain Baby Pokémon.
 * Despite the fact, that Pokémon Eggs don't use slots in items bag, they cannot be obtained from PokéStop when the bag's slots limit is exceeded by items.
 * There are several bug related mostly, to weak network connection during the gameplay, that allows player to see the most recently hatched Pokémon in their Pokémon collection or Journal before even seeing notification nor animation of hatching egg.
 * There is significant relation between Buddy distance for candy reward of specific Pokémon and what kind of egg it hatches from, as:
 * Pokémon that hatch or originally hatched from 2-km Eggs have to walk 1 km for candy reward,
 * Pokémon from 5-km Eggs have to walk 3 km for candy reward,
 * Pokémon from 10-km Eggs have to walk 5 km for candy reward
 * and Legendary Pokémon that don't hatch from any egg have to walk 20 km for candy reward.