The interface section of a unit is the public part.

It determines what is visible and accessible to any program (or other unit) using that unit.

The interface section starts at the reserved word interface, which appears after the unit header, and ends with the reserved word implementation.

In the unit interface, you declare constants, data types, variables, procedures, and functions.

The "bodies" of public procedures and functions are in the implementation section.

Forward declarations are not allowed.

A uses clause can appear in the interface section. (If present, uses must immediately follow the reserved word interface).