First, you start with a complete backup of all files on every computer. After that, only new or modified files are backed up.
Incremental backups are much faster and use much less media storage space than full backups.
Because until now, restoring lost data from incremental backups has been a challenging multi-step process, often requiring the expertise of an IT pro to navigate the system. Retrospect changes that by copying only what you'll need for a reliable restore. One-step restores are so easy, even an entire hard disk can be recovered in a single step even after hundreds of incremental backups. Backup just got better. And we never quite recover all our files.