File used by Newzbin, a service that indexes Usenet contents; contains short summary information about a Usenet posting, such as a unique ID, poster name, posting groups, file names, and file segments; used as an index to gather newsfeed content from a Usenet posting.

NZB files download headers specific to a user's search instead of all headers in a newsgroup. They help save time and bandwidth since they do not require updating the entire newsgroups list. NZB files are stored in an XML format.