The new creep

Probably one of the most defining characteristics that set the Zerg apart from the other races is the Creep: the organic ground that serves as the nourishment and lifeblood of Zerg structures and buildings. However, this time in Starcraft 2, the creep has evolved to something far more.....

Features of the Creep

1) Creep allows building of Zerg structures - obvious feature. You can only build Zerg structures on Creep and nothing else besides the Hatchery and the Extractor. Even Spore and Spine Crawlers can only root in Creep. Note that just as you, a Zerg player can build on Creep, so can other Zerg players. Keep that in mind while playing ZvZs.

2) Prevents other races from building on the creep - this means that if your opponent is for example, a Terran, he cannot indefinetly bunker push into your base because bunkers cannot be built on Creep. Keep in mind that this feature also affects allies (that are not Zerg) meaning allies cannot build on Creep.

3) Grants a 30% movement speed bonus to all Zerg units - This does not include drones and air units, but DOES include all ground units, even those that can burrow and move. Creep affects you, as much as it affects every other Zerg player. This movement speed bonus is probably the most important to consider as a mechanic. Take the Hydralisk. It no longer has that movement speed upgrade and goes slower than you might want it to go when not on Creep, but ON IT, it moves at a pace similar to an upgraded Hydralisk in Brood War. Essentially making "Creep highways" is very effective for quickly getting Zerg units where they need to providing a huge macro bonus. At the same time, you can more effectively micro units if they have higher speed. Take Roaches against Zealots. Faster moving Roaches can quickly move back, allowing you to have more time and shots to hit Zealots. 30% is quite a bit of speed to consider.

Myths of the Creep

1) It is widely believed that creep provides a regeneration bonus to Zerg units. It doesn't. This rumor was started by sc2 armory which spread that news from the early meta builds of Starcraft 2. It is highly unlikely that there is a regeneration bonus (or even a slightly noticeable one otherwise higher tiers would report on it).

2) Creep doesn't attack structures. This was an idea early in the Alpha builds and then scrapped. 

Spreading Creep

There are two ways to spread Creep, effectively replacing the Creep Colonies from Brood Wars

1) Queens - Creep Tumor: These spawn from the Queen for 25 energy. Once the Creep Tumor sets up, it then burrows into the ground (only revealed by detectors - it can be killed) and allows one more creep tumor to be set up (within a certain range of itself). You can essentially create endless Creep for just 25 energy once, and then spend time getting those Creep Tumors.

2) Overlords - Generate Creep: When you upgrade to Lair, all Overlords (not Overseers, upon metamorphosis, Overseers lose this ability) gain the ability to generate Creep. This costs no energy and only requires the Overlord to stand still while it does it's business. This is also an ability that can be left on at all times, so that whenever the Overlord comes to rest, it generates the Creep

Strategies:

The main reason why this guide is set up, is not just to provide a basic overview of the Creep, but to realize that it is essentially another mechanic to be mastered. Not many players tend to use Creep aggressively, despite it's benefits.

You can use it to block of expansions. You can have an Overlord generate Creep, essentially serving as a scout for you. If they destroy/chase away the Overlord, it takes a while for all that Creep to disappear (usually 30 seconds) giving you an extra 30 seconds where a non Zerg cannot build an expansion. Alternatively you can also have a Queen use a Creep Tumor and deny access this way or a combination where the Overlord generates a small area of Creep and then the Queen plants the Tumor to keep it permanent.

You can fool opponents. Aggressively using Creep, you keep the opponent guessing where your base is. There is a difference between an area you control (using Creep e.g a Creep highway) and an area where all your workers are mining resources, where all your critical structures are etc. It's not much, but useful.

Faster movement speed is always a great bonus. As I mentioned earlier, Hydras are very effective when on Creep, it allows faster base response time, faster rallying, better micro-ing etc. It even affects burrowed units, so you can essentially have burrowed Roaches move faster, keeping the element of surprise.

When bringing in an attacking force, bring in some Overlords, and have them generate Creep while attacking an enemy base. That faster speed does come in handy when micro-ing and rallying. You don't even need to give them a command, just toggle generate Creep and whenever the Ovie stops, it puts down some Creep.

Creep helps melee units. Ever seen Zerglings with speed upgrades? Know how fast they are on Creep? The faster the melee units like your Zerglings and Ultralisks move, the less damage they take from ranged units and other types of attacks. Even evading Psi Storm becomes easier.

Lastly, think Blizzard just meant to have the Zerg have these new mechanics because nothing looks more alien, more scarier, more cool than Zerg players infesting large portions of the map with their Creep.

Video: Oversky vs Artosis - Note how Oversky aggresively uses Creep and creates his Creep highway.

As I get in more strategies, and myths, I'll keep uploading more tips, put in some pictures and videos of how Creep should be used. Thanks for your time!