Function Names as Expressions
The ability to treat the names of functions just like other kinds of expressions is an important consequence of the symbolic nature of the Wolfram Language. It makes possible the whole range of functional operations.
Ordinary Wolfram Language functions such as Log or Integrate typically operate on data such as numbers and algebraic expressions. Wolfram Language functions that represent functional operations, however, can operate not only on ordinary data, but also on functions themselves. Thus, for example, the functional operation InverseFunction takes a Wolfram Language function name as an argument, and represents the inverse of that function.
Unless you are familiar with advanced symbolic languages, you will probably not recognize most of the functional operations discussed. At first, the operations may seem difficult to understand. But it is worth persisting. Functional operations provide one of the most conceptually and practically efficient ways to use the Wolfram Language.