게

Makes a word into an adverb

Turns a describing word into how the action is done, the job English does with "-ly": kindly, safely, deliciously, awkwardly. It is also the piece inside the everyday words for "like this" and "how", which are so common in spoken Korean that they account for most of the examples here — a speaker saying "you can use it like this" is using it. A different 게 that sounds identical means "the thing that", a squeezed-together noun plus subject marker; that one sits after a verb-describer, not on a describing word.