What is reflect-metadata in typescript

what are reflect-metadata and its purpose?

What is syntax and purpose of using reflect-metadata?

Can some one provide the example for better understanding of the same?

How can be the reflect metadata helpful in implementing decorators in typescript.

reflect-metadata Allows you to do runtime reflection on types.

The native (non reflect-metadata) version of type inference is much poorer than reflect-metadata and consists only of typeof and instanceof.

More

This blog post covers its features well : http://blog.wolksoftware.com/decorators-metadata-reflection-in-typescript-from-novice-to-expert-part-4