A logical drive on a computer is designated by the drive letters in the My Computer window or Windows Explorer window in the Microsoft Windows operating system. Computers have a C drive, which is a logical drive designated as "C:". Some computers have additional logical drives, depending on how they were setup by the manufacturer.
When a hard drive is initially set up in a computer, it defaults to being the C: drive. Additional logical drives can be set up by partitioning the physical hard drive. Each logical drive can be set up as a different size, but they are all still part of the one physical drive. Each logical drive can be used to store different types of files or even to install different operating systems, providing an option to boot to various operating systems. It's also possible to set up one logical drive with a NTFS file system and another with a FAT32 file system, if needed.