The file extension PLUGIN is linked to the operating system Mac OSX from Apple. Plugin files add extra functionality or additional hardware support to Apple Mac OSX programs. Common PLUGIN files for the operating system are usually stored in the main library folder, for example, Library / Internet Plug Ins. Others, which only provide functions for certain programs, such as Quicktime or Adobe Soundbooth, are stored directly in the respective application folder.
However, this is only a voluntary mark on the part of the creator. Since the Mac is not dependent on endings, many plugins have no extension.
Most often resolving problems with opening PLUGIN files is very simple. Just install an appropriate program that supports such files. All of the listed programs support PLUGIN files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of PLUGIN files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate PLUGIN files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the QuickTime Player applications is not on the list, select "Browse" option in order to manually locate the directory where QuickTime Player has been installed.
Sometimes problems with opening PLUGIN files may not lie with the application itself, but can arise due to other causes, such as: