A mount may refer to any of the following:
1. Before an operating system can read from or write to a disk, the file system on one of the disk's partitions must be mounted. A "mounted" disk is available to the operating system as a file system for reading, writing, or both.
When mounting a disk, the operating system reads information about the file system from the disk's partition table and assigns the disk a mount point. The mount point is a name that refers to the disk, like "C:" in Microsoft Windows or "/" in Linux, BSD (Berkeley Software Distribution), macOS, and other Unix-like operating systems.
For instance, in Microsoft Windows, mountable file systems are called volumes. Mounted volumes are listed in File Explorer in the section named "This PC" (in Windows 10) or "My Computer" (in earlier versions of Windows). Every mounted volume is assigned a drive letter.
Automatic vs. manual mounting
Windows and macOS, by default, automatically mount every disk attached to the computer. For instance, when you insert a USB (universal serial bus) flash drive, the OS (operating system) detects the new storage media, attempts to mount it, and if it can, it does. Other operating systems, such as Linux, require you to explicitly configure mount points (in the file system table file, /etc/fstab) or mount the disk manually with the mount command.
5. Mount may refer to a group of files in a file system accessible to a user or group of users.