Spider-Man has altered the design of his web-shooters over the years.
Currently he can activate his webbing by apply the specific pressure of his middle and ring fingers to the centre of his palm when his hand is bent back. his prevents the web-shooters activating when he presses his palm against a surface or makes a fist.
Different types of webbing can be activated depending upon the number of times he taps the trigger in quick succession.
One tap=Standard web-line
Two taps=An expanding web net to collect debris and wrap up opponents
Three taps=A thick spread used to make protective barriers like web shields
Four taps=His own lower calibre versions of Ben Reilly’s impact webbing designed to wrap up opponents upon connecting with them
Five taps=A variant of the impact webbing designed for offensive concussive purposes.
The number of taps required in indicative of the frequency of his use of that type of webbing and how vital it is to his superhero activities. For example Peter requires just one tap to trigger the standard web-lines because he uses this form of webbing for everyday transportation. In contrast he decided the concussive form of impact webbing should require five taps. This is because it is the most overtly offensive form of his webbing and so he wanted to make sure he’d never accidentally trigger it and use it only when necessary.
Once Spidey has tapped his palm to trigger any type of webbing he can immediately cancel the command by releasing his middle finger but keeping his ring finger pressed down for at a minimum one millisecond.
By tapping his palm with his middle, ring and pinkie fingers he can shoot out a micro-dot spider tracer at his opponents, though he equally carries some in one of his belt compartments.
Though at one point (ASM #295) Peter designed his web-shooters to incorporate an LED light to alert him whenever his webbing was starting to run low, he abandoned this feature as the apparatus was continually damaged in the course of the natural wear and tear of his super hero career, thus proving useless and a wast of money.
