What’s actually going on is that the small electrical charge coming from the object or person triggering the switch causes a change in capacitance, effectively disturbing the existing electrical charge contained within the minute wiring of the switch itself. The switch can ascertain from this change in electricity flow precisely when, where and how it was pressed, and thus trigger the corresponding function(s) it’s been wired to perform.
Capacitance touch switch circuits work with human skin precisely because it’s electrically conductive (after all, our bodies are mostly made up of water) - and that’s also why they work with pretty much anything else that holds a small amount of electrical charge. For this reason, you’ll often find you can operate a capacitive touch switch with any number of random objects held in the hand, rather than with your hand itself.
A bar of soap or a chunk of freshly cut potato, for instance, will operate a standard touch lamp perfectly well - whereas you’ll get nowhere trying to turn it on and off with a piece of stone, dry wood or fabric. If the object in question happens to be an effective enough insulator, it will block the flow of electricity between you and the switch and no actuation will occur. For this reason, objects intended explicitly for the manipulation of touch switches (a stylus, for example) must be specifically designed to be capacitive too.
Capacitive touch switch kits can be used in a very broad array of applications and environments, including everything from smartphones and industrial controls to vending machines and common household appliances. They’re frequently found incorporating a wide range of other features, such as LED backlighting and IP ratings, making them among the most widely used touch switch types in harsh environment settings.
The lack of mechanical (i.e. moving) parts in a true capacitive touch switch means they’re generally seen as particularly robust, durable and reliable options, suitable for a range of industrial and outdoor applications in all manner of different panel and screen types.