they = plugins?
Depends who makes the plugin, for flash player once installed its c:\windows\systems32\macromed\flash\
in there you will find NPSWF32.dll which is the plugin, along with its updater, un-installer, an activex file and flashplayerutil
You get flash initially by being linked from a website that needs it, or directly from the macromedia website...http://get.adobe.com/flashplayer/
Before installing it have a read of this thread and its subsequent pages, a lot of information regarding privacy issues using flash and towards the end something else has been found out since adobe bought omniture and will be using ActionSource.....https://nodpi.org/forum/index.php/topic,1969.0.html