Subroutine - A set of program instructions performing a specific task, but which is
not a complete program. It must be incorporated into a program to be used.
Parameter - Information about a data item being
supplied to a function or procedures when it is called.
Preconditions - Specifying preconditions ensures that the user knows what
checks, if any, must be performed before calling the subroutine.
DLL - A Dynamic Link Library is a collection of small programs, any of
which can be called on when needed by a larger program.
Caching - Temporary storage of program instructions that
have been used and may be needed again.