A newsreader is an application program that reads articles on Usenet distributed throughout newsgroups. 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 also used to distribute binary files, generally in dedicated "binaries" newsgroups. The term newsreader is sometimes (erroneously) used interchangeably with news aggregator.