Glossary » user-extensible systems
software that allows users to add functionality, usually by allowing the user some level of scripting capability, but also by allowing the user to add resources (extensions, fonts, images, etc). Unix shells often allow users to add commands by writing scripts. Many programs, such as Photoshop, allow users to create macros that are incorporated in the application from then on. Web browsers not only allows plug-ins to be added, but are extensible in the way that they allow bookmarks to be added and organized.