How to get the posts xml/json format based on the tag/tags?

Hi ,

Can anybody know how to retrieve the posts in xml/json format based on the tag/tags selected in my community.

These are the listed tags suppose i have.  If I select any tag or multiple tags , i need the posts in xml/json which are tagged with the selected tag or multiple tags.

Can anybody help me on this please.

The exact REST API call to pull the posts based on a particular tag.