| Backup pair | The saved relationship between one or more source folders, one destination and the rules between them: schedule, retention, filters and security. Also called pair. |
| Catch-up run | A run that O&O AutoBackup starts after a missed or deferred run, as soon as the blocking condition clears, for example when the drive is connected again. |
| Conflict | In synchronization, a file that changed on both sides since the previous run. The conflict policy under Advanced decides which copy wins. |
| Continuous mode | A schedule that watches the sources for changes and starts a run after a short quiet period. |
| Copy | Synchronization mode that copies new and changed files from left to right and never removes files on the right. |
| Destination | The storage that receives the protected copies: a separate internal disk, USB drive, network share, WebDAV server or S3-compatible storage. |
| Destination folder | The subfolder below the destination that O&O AutoBackup proposes from a template, for example Backup; shown as Destination path in the wizard. |
| Encryption | Optional protection of a backup: each file is encrypted with AES-256-GCM using a key derived from the password. Fixed once the backup has run. |
| File group | A filter that collects file extensions such as office documents, pictures, music or video, used to copy only certain types from a source. |
| Left and right | The two sides of a pair. In one-way modes the left folder is the source and the right folder the destination. |
| Managed thinning | The retention policy that keeps every version from the last hour, then one per hour, one per day and one per week, while the newest copy of every file always stays. |
| Merge | Synchronization mode that copies new and changed files in both directions until both folders contain the combined set; deletions are not propagated. |
| Mirror | Synchronization mode that makes the right folder an exact replica of the left, including deletions. |
| Name hiding | The option Also hide file names and folders: stored files receive random names and the folder structure is kept in an encrypted index. |
| Offline copy | A backup copy that is not reachable from the PC or the cloud account all the time, for example a USB drive that is disconnected after the backup. |
| Online-only file | A OneDrive file whose contents are not stored on the PC (Files On-Demand). It has to be downloaded before it can be backed up. |
| Portable recovery app | The application Recover this backup that O&O AutoBackup stores beside a backup. It restores that backup on another PC without a license. |
| Preview | The summary of files to create, update, move, delete or skip that a synchronization shows before it changes anything. |
| Recovery key | A key generated when encryption is enabled. It unlocks the backup if the password is forgotten and must be stored separately. |
| Repair file list | The action that rebuilds the recorded state of a destination after its files were changed outside O&O AutoBackup. |
| Restore point | A point in time in the restore view. It shows the files as they existed at that moment, including files deleted later. |
| Retention | The rules that decide how long earlier versions are kept: managed thinning, optional limits by age or count, and available destination space. |
| Source | The folders whose files are protected. |
| Synchronization | A controlled way to make two folders agree in the Copy, Merge, Mirror or Two-way mode. It keeps no version history and is not a backup. |
| Two-way | Synchronization mode that applies new files, edits, renames and deletions from either side to the other. |
| Vault ID | The identifier of an encrypted backup. It is printed on the recovery sheet so that the recovery key can be matched to the right backup. |
| Version | The previous copy of one file, set aside under a date-stamped name when a run replaces it with a newer one. |
| Version history | All stored versions of the files of a backup; it allows restoring an earlier state or a deleted file. |