A directory is made up of files. Each file may have many records, each record many fields, each field many bytes.
Expressions give rise to statements, grouped into functions, libraries, and then applications.
The ability to operate over so many levels of abstraction is arguably one of the traits that makes us human. Managers who can move up and down levels of abstraction will be able to use this skill easily and effectively in dealing with people, even those who are not programmers, provided they understand some simple principles. But first some terminology. As we get more and more abstract, we deal with larger and larger chunks of data. As we get more concrete, we deal with smaller and smaller chunks of data.