In the Mac OS, an application for managing Control Panels, Extensions, System Folder items, Startup Items, and Shutdown Items.
You can view and sort by location (one of the afformentioned folders), name, on/off status, size, version, and package name. For most items, you can also view metainformation. So where a Windows user might see wtfisthis.dll, a Mac user in the Extensions Manager might see, under the Extensions heading,
DVD Navigation Manager 1028k 2.1 Apple DVD Software 2.1
This extension is used the the Apple DVD Player to enable software playback of DVD movies.
You can maintain separate sets of extensions and control panels. You might want to have an optimized group of settings for gaming, for instance. There are also premade (and write-protected) sets that reflect the "Base" and "All" Mac OS settings.
The Extensions Manager is also useful in troubleshooting. If you've installed a new application and then find that your machine is suddenly flaking out, an extension conflict is a likely culprit. You can use the Extensions Manager to help isolate the conflict.
You access the Extensions Manager through the Apple Menu. To invoke the Extensions Manager on startup, press and hold down the space bar after the startup chime.