Extractor trick - getting an extra drone

This is a relatively simple Zerg technique, seemingly obvious yet very few use it, and easy to implement in the game. You know how you spend Drones on buildings rather than drones building them? You can use that to your advantage in very early game as a Zerg player. 

You start out with 6 drones and 10 supply (to be replenished with Overlords). On your 9th or 10th Drone, you get either your Spawning Pool (called "9 Pool", "10 Pool", early Pool) or get an Overlord. Getting more Drones is not an option till you get your second Overlord, and you certainly cannot have 11 Drones immediately before getting that second Overlord spawned. OR CAN YOU?

An Extractor costs 25 minerals. So get your 10th Drone to morph an Extractor. When it starts morphing, supply goes down by 1, allowing you to spawn a Drone. Then cancel that Extractor, and the Egg morphing the 11th Drone is still intact, and you can time an Overlord at the same time. 

This allows you to get an extra Drone out faster. Very useful in ZvZ, or any other matchup to give that small yet crucial economic edge in the early game. This can be applied later as well, but it is most useful in the early game so I suggest that you do use this.

This technique is practiced by quite a few pros. In Team Liquid's Starcraft 2 Invitational, in this game of Lost Temple of White Ra (Protoss) vs TheLittleOne (Zerg), the Zerg player shows off this trick.