Removal of viruses, etc. & factory or junk apps/data to increase speed & battery life.
Transfer or Backup of all your devices data to a new device.
Data available to transfer will vary if devices have different Operating Systems.
Store all your data on a external storage drive or PC of your choice in case the unthinkable happens. Data includes all Apps & App data, Messages, Contacts, Call Logs, Pictures, Videos, Music, etc.
Apps & App data are not transferable to different operating systems as well some videos.
Some downloads and interaction from owner may be required for remote service.