Web-Shooters were created by Peter Parker to fire spider webs.
After the spider passed on the knowledge of what chemicals to use to create webbing. Peter then created a web fluid that he placed in a small cartridge and a pair of Web-Shooters. The cartridge would be placed in the Web-Shooter and would fire a web when Spider-Man would press the trigger with his two middle fingers.
According to Spider-Man the webbing only lasts for about an hour before it starts to dissolve.
The webbing could also be fired two different ways from the web shooters. The first way is that the web could be fired as a thin web line and the second way was as a wide spread.
The webbing could be formed into various objects such as a net, a parachute, a swing, or a bag that Peter used to store his clothes in.
Peter Parker later created a special type of web fluid to use against Hydro-Man. This new type of web fluid hardened when exposed to water. Spider-Man would use this to harden Hydro-Man's liquid body so that he could not move.
Green Goblin was so strong that he was able to crush Spider-Man's Web-Shooter's by simply squeezing his wrists.