Some people consider the Photon Cannon rush a 'cheese strategy'
. I view it as a legitimate strategy simply because if your opponent scouts you properly he can easily stop the cannon rush.
However, we don't want them to spot it, that's part of our strategy after all. If you successfully execute this strategy you will systematically destroy your opponents base with ease.
The Cannon Rush Build Order:
Pylon
Forge
Photon Cannons
Pylon
Gateway (shouldn't need this)
That's it, this strategy doesn't require any special economic micromanagement. You only need to build a few Probes and the rest takes place in your opponents base.
First you need to bring 1-2 Probes to your opponents base. I normally bring 2 Probes in case something happens to one of them. Once your probes arrive there are a lot places you can do this but I recommend you try and place your Pylon just outside your opponents area of vision. Make sure you are still close enough so you Photon Cannons can be in range of your opponents Nexus, Command Center, or Hatchery.
Make sure to place your Pylon in a place were your opponent won't notice it. If he does notice it he will surround it with his workers and destroy it.
Once your Pylon is complete, start building Photon Cannons as fast as you have minerals. Slowly build one cannon in front of another. This strategy will keep your newest Photon Cannon safe because other ones further back can cover it. Just keep dropping Photon Cannons closer and closer until you are in range of his Nexus, Command Center, or Hatchery.
Once you have a few cannons down it will probably be game over for your opponent. It's almost impossible to comeback with a bunch of Photon Cannons in your base. This strategy can be tough to use on a Zerg player since you can't build on Creep. But if you are creative with your cannon placement you can still take out Zerg players.
You can find many more Starcraft 2 strategies and reviews of some of the most popular Starcraft 2 guides at my website.
Best of luck to you. I look forward to seeing you on BattleNet!