The same as in JavaScript, functions are the processing machines where we analyze input, digest information, and apply the necessary transformations to the data provided to either transform the state of our application or return an output that will be used to shape our application's business logic or user interactivity.

Functions in TypeScript are not that different from regular JavaScript, except for the fact that functions, just as everything else in TypeScript, can be annotated with static types and thus, they better inform the compiler of the information they expect in their signature and the data type they aim to return, if any.