The Zerg rush is one of the fastest ways to end a game of Starcraft 2. Build a small tactical force of zerglings and rush your enemies base to catch them with their pants down. Not only the fastest way to victory but the fastest way to infamy. Most non Zerg players will hate you for using this tactic.
Although this Zerg strategy appears very simple at first glance it has some fine points to it. Ignore these and you won't get far with it.
Because you are going for a quick attack with your zerglings you are making some sacrifices to your home base defenses and your economy. If you don't get the most out of your zerg rush you are left in a very vulnerable position. You must have a fall back plan or you may wind up looking like a total dork.
This starcraft 2 zerg strategy should be viewed as a way to damage your enemies economy early in the game to give you an edge. But you don't want to just send your zerglings blindly rushing into the enemy base trying to take out the supply line. The basic worker units, Drones, Probes and SCV's can easily kill zerglings so you need to have control over your zergling army. Don't let them get surrounded.
Terran players usually block off their base and turn turtle. Break through the choke point, watch out for Marines and take them out. Remember hit and run. Take out units that can hurt you. Then cut off the money tree.
If a Protoss opponent gets a few Zealots out then you better start rethinking things and fall back to plan B. Maybe more of a harassing tactic to mess with their head. All the while popping more zerglings for a steady zerg rush of six at a time. If you can take out the Zealots then work on the Pylon that is powering the Gateway. Then destroy their supply line.
When facing a Zerg player you will most likely be battling Zerglings but you will need to scout. Get the Speedling upgrade as soon as possible to get the advantage.
If your Zerg rush is a success be ready for some abuse. Your opponent will probably be pissed at you for spoiling their fun. Don't worry if at the beginning of the game they try to set a bunch of time limit, no rush BS. Just rush any way. You're there to win. The races are evenly balanced overall and the Zerg have an early game advantage. Use it. Be aware that you will be exposing yourself to attack by having a weaker base and economy at first. All's fair in love and war and the Zerg got no love.