A newsgroup is an online discussion forum that allows users to post messages and share information on specific topics. These groups are part of the Usenet system, which has been around since the early days of the internet. Users can read and respond to messages, creating a community around shared interests. Newsgroups are organized into categories, making it easy to find discussions on various subjects, such as technology, science, or entertainment. Each newsgroup has a unique name, often following a hierarchical structure, which helps users navigate the vast array of topics available.