These are backups that are ongoing or done continuously or frequently to a storage medium that is always connected to the source being backed up.  Typically the storage medium is located offsite and connected to the backup source by a network or Internet connection. It does not involve human intervention to plug in drives and storage media for backups to run. Many commercial data centers now offer this as a subscription service to consumers. The storage data centers are located away from the source being backed up and the data is sent from the source to the storage data center securely over the Internet.

Online Backup