An NNTP Server (Network News Transfer Protocol Server) is a type of server that facilitates the distribution, retrieval, and posting of news articles and messages in newsgroups. It allows users to read and post content in a decentralized manner, enabling discussions on various topics across the internet. Users typically access an NNTP Server through newsreader software, which connects to the server to download and upload messages. This protocol supports multiple users simultaneously, making it an efficient way to share information and engage in conversations within online communities.