The Internal or Physical Level
The collection of files permanently stored on secondary storage devices is called as the physical database. The internal or physical level is the one nearby to physical storage, and it gives a low-level description of the physical database, and an interface among the operating systems file system and the record structures used in higher levels of abstraction. It is at the level that record types and methods of storage are definite, as well as how stored fields are shown, what physical sequence the stored records are in, and what other physical structures exist.