A newsreader is an application program that reads articles on Usenet (a distributed discussion system, which groups its content into a hierarchy of subject-related newsgroups, each of which contains multiple threads or discussions). Newsreaders act as clients which connect to a news server, via the Network News Transfer Protocol (NNTP), to download articles and post new articles. In addition to text-based articles, Usenet is increasingly used to distribute binary files, generally in dedicated "binaries" newsgroups.
The term newsreader is sometimes (erroneously) used interchangeably with news aggregator.
There are several different types of newsreaders, depending on the type of service the user needs—whether intended primarily for discussion or for downloading files posted to the alt.binaries hierarchy:
- Desktop newsreaders
- Designed to integrate well with common GUI environments, and often integrated with a web browser or email client. Examples: Windows Live Mail, Mozilla Thunderbird, Xnews, Forté Agent, Unison, Newswatcher and Pan.
- Traditional newsreaders
- Designed primarily for reading/posting text posts; limited and often cumbersome binary attachment download functionality. Gnus, as well as more specialized newsreaders such as slrn, nn and tin.
- Binary downloaders
- Although Usenet originally started as a text-based messaging system without any file attachment ability, many Usenet users today do not participate in discussion groups, as was common during the 1980s and 1990s and only use Newsgroups for downloading files such as music, movies, pornography, software and games. Therefore, their needs call for a streamlined client for quickly grabbing binary attachments, and without the extraneous clutter of text reading and posting features for which file downloaders have little use. Examples: GrabIt, NewsBin