This list of computer size categories attempts to list commonly used categories of computer by the physical size of the device and its chassis or case, in descending order of size.
One generation's "supercomputer" is the next generation's "mainframe", and a "PDA" does not have the same set of functions as a "laptop", but the list still has value, as it provides a ranked categorization of devices.
It also ranks some more obscure computer sizes.
[1][2] These are mainly used for scientific calculations or simulations and processing big data with high precission.
[2] This is a very broad categorization that includes computers with a single microprocessor as their central processing unit (CPU).