GGPO An online gaming portal

What is it?
GGPO is a networking library that game developers can use to add networked gameplay support to arcade style games. GGPO's latency hiding techniques give each player a gameplay experience that is nearly indistinguishable from playing with their friends locally, even against players around the world.
How does it work?

GGPO uses a peer-to-peer topology to run a complete copy of your game for each player, transmitting controller inputs over the network to keep these copies in sync. Each player's inputs are sent to their copy of the game without having to wait for their opponent's to arrive over the network.

If the simulations diverge, GGPO rolls back to the most recent accurate state, corrects the mistake, and jumps back to the current frame, all before the player can notice. This provides the illusion of lag-free game play.
How does it perform?

Thousands of gamers are already using GGPO to play classic, old school fighting games against opponents around the world. GGPO's latency hiding techniques maintain the illusion of lag-free game play even during intercontinental play.
So lets start for online gaming. You need to download and install first adobe AIR along with ggpo client.Then download rom files from Rom-World and copy these roms in C:\Program Files\GGPO\Roms folder make rom folder by yourself.
     Adobe AIR
     GGPO client
  After installing ggpo client run it and make a account on GGPO. Now login into ggpo client using your details. Disable any firewall if enabled.Now you are into main lobby of GGPO which looks like in picture below: 

        Now you can click on your favourite game in left column and a room will open central column is for displaying chat in room.
The right column shows available players whom you can play.
   How to play with players?
  Playing against a player is not too much difficult click on the name whom you want to play then a request will be sent to that player if he accepts your challenge then game will start.
  How to configure keys?
 During game play starts press F5, a key setup will open now configure your keys there.
   How to onscreen chat during game play?
 WE can chat during game play.Simply press "T" key and enter after writing your message.
   Keep enjoy your classic gaming experience with WHOLE WORLD.