Program Organization Delphi programs are usually divided into source-code modules called units. Most programs begin with a program
heading, which specifies a name for the program. The program heading is followed by an optional uses clause, then
a block of declarations and statements. The uses clause lists units that are linked into the program; these units,
which can be shared by different programs, often have uses clauses of their own.
The uses clause provides the compiler with information about dependencies among modules. Because this
information is stored in the modules themselves, most Delphi language programs do not require makefiles, header
files, or preprocessor "include" directives.