What's a Plug-in?

Plug-in

Pros and Cons
Macro, which empowers it's host program. 'Make CorelDRAW and Illustrator cut'
It works like a genuine part of its host program either as a toolbar or a submenu. It extends it's host program with special sign tools, like multi copy, contour, outline, ..., which are originally not included.

Example:  

Sign Program

Pros and Cons
A plug-in's counterpart is a sign program.
A sign program includes plotter drivers with all tools for designing, editing and cutting of signmaking jobs. Unlike with the classic illustration programs such as CorelDRAW, Illustration and Freehand, all tools are tailored to the special requirements of signmakers.

Example: