NZB (also known as NewzBin or Newzbin2) is an acronym for "Newzbin Usenet Index", a website which indexes Usenet posts and makes them available for download. The website indexes posts that are in the NNTP (Network News Transfer Protocol) format, which is a common format used to share news and other information over the internet. Usenet is a distributed system of newsgroups that was first developed in the early 1980s. It allows users to post and download messages to and from thousands of different newsgroups. NZB is a type of file format used to store Usenet posts. It is a binary file format which can be used to quickly identify the posts that are needed for a particular download. NZB files are used in conjunction with news readers and downloaders, such as SABnzbd or NZBGet, which can download the files from Usenet servers. NZB files are also used to identify content that is shared on Usenet, such as books, music, movies, and software.
Discontinued development for Unison has been discontinued and the software is no longer maintained, but the latest version has been released as free by Panic.