ownCloud is a free software developed by the KDE community that provides private Web services. The current main functions include file management (built-in file sharing), music, calendar, contacts, etc., and can run on PCs and servers. Simply put, it is a self-built network disk based on Php. This is basically for private use, because the development version has not exposed the registration function until now. The official website also provides a synchronization client that can be downloaded, covering multiple operating systems. This is a version with minor improvements and bug fixes. Added drag-and-drop window under Firefox.