Use metadata to tell NestJS what your classes, methods, and parameters are supposed to do.
Decorators are a major part of how NestJS keeps backend code readable. Instead of configuring everything separately, you can use decorators such as @Controller(), @Get(), @Injectable(), and @Body() to describe how different parts of your application should behave.
NestJS uses this metadata to build and connect your application at runtime. Once you understand decorators, many NestJS features become easier to understand because you can see that they are essentially instructions telling the framework how to treat your code.
What you'll walk away knowing