They have a tactile bump feeling with a distinctive ‘click’ sound. Ideal for efficient typing and data entry because you don’t need to fully depress the keys.
It has an actual physical switch underneath each key. The switches are composed of several parts including a plastic stem, two metal contacts, and a spring. This is a more complex system than in standard keyboards, which have a membrane with electrical contact points. Mechanical keyboards tend to offer much better feedback, a more satisfying keypress, and a longer lifespan.