Jira Core Server is a self-hosted version of Jira Core, which is a project and task management software developed by Atlassian. It's designed to help teams and businesses organize, track, and manage their work and projects. Jira Core Server allows organizations to install and run Jira Core on their own servers or infrastructure, giving them more control over the software and data. It's a popular choice for businesses that have specific security or compliance requirements. Keep in mind that my knowledge is based on information available up to September 2021, so there may have been updates or changes to Jira Core Server since then.