Hatcheries perform three vital functions that no colony can survive without: producing the creep, which most zerg structures require in order to be built, giving birth to larvae that can mutate into the various zerg breeds and digesting minerals and vespene gas to change into a nutrient form that zerg can use to feed their mutations. In addition, the hatchery is one of the only structures that can be built without pre-existing creep (the other being the extractor) and is therefore essential for any expansion attempt.
The zerg continue to use hatcheries in StarCraft II. Hatcheries continue to be able to create creep. Upgrades for overlords and overseers are researched at the hatchery and its evolved forms, but at least a lair is required first. This change allows the player to research the upgrades at any hatchery they control as long as they have a lair, rather than being limited to researching them at the lair itself.
If multiple hatcheries are selected, pressing the "S" hotkey will select all of the available larvae at all the selected hatcheries. The player must press a hotkey (or select a morph icon) once for each unit they wish to build.
Two rally points are able to be set on a hatchery; one ("G") for drones and another ("Y") for warrior units. The queen doesn't get a rally point.
Each individual egg can be separately rallied; this overrides rally points set for the hatchery.
A hatchery spawns a new larva every 15 seconds if there are less than 3.
Queens can target a hatchery/lair/hive, causing it to eventually spawn four larvae. These join any already-present larvae. The larva-producing structure will not naturally produce any more larvae until the total falls below three. The larva count for any given hatchery/lair/hive cannot exceed nineteen, no matter how many times spawn larva is cast.
↑"for zerg is it the same that the hatchery sets the rally, or can you rally for each individual egg?"
You can do both. You can set a rally for your hatchery, but can then override it with manual orders per egg as well. Also don't forget, you can set a worker rally point for your hatchery, as well as a unit rally point. Karune, Rancid_death75. Another rally question for Kaurne!Battle.net StarCraft II General Discussion Forum. Accessed 2009-02-18.
↑Blizzard Entertainment Staff. 2010-07-24. Infestor. Blizzard Entertainment. Accessed 2010-07-24.