A Kotlin composable function describes some part of your UI.
Doesn't return anything.
Takes some input and generates what's shown on the screen.

In Kotlin, a composable function is a special type of function used in Jetpack Compose, which is a modern UI toolkit for building Android applications. Composable functions are used to describe the UI of an application by defining individual UI components or elements.

The key characteristics of a Kotlin composable function, based on the description you provided, are as follows:

1. Describing UI: Composable functions are responsible for describing a specific part of the user interface. Each composable function represents a self-contained UI component, such as a button, text field, or a more complex layout. By composing these functions together, you can build the entire UI hierarchy of your application.
2. No return value: Unlike traditional functions that may return a value, composable functions do not have a return type. Instead, they use a special type called @Composable from the Jetpack Compose library. This indicates that the function is a composable function and that it directly affects the UI composition rather than returning a value.
3. Input and UI generation: Composable functions take input parameters, which can be used to customize the behavior or appearance of the UI component being defined. These parameters could include text, colors, images, or other data necessary to generate the desired UI. Based on the provided input, the composable function generates the corresponding UI elements and defines how they should be displayed on the screen.

By following these guidelines, composable functions help in building declarative UIs. This means that the UI is defined based on the current state and inputs, and any changes to the state will automatically update the UI. Compose takes care of efficiently updating only the necessary parts of the UI when the underlying data changes, resulting in a more performant and responsive user interface.