What's a Confluence Gadget?

Years ago I disabled a bunch of system plugins relating to gadgets somewhat out of paranoia coupled with the fact I didn't see a need for people putting garbage in our wiki that connected to 3rd party sites. It just seemed fairly useless yet a great opportunity for security flaws. This was back on Confluence version 3 something. Back then I remember seeing a bunch of junk available to the end user labeled as "gadgets" that just seemed dumb.

Now we've upgraded to 4.3.7, and based on some weird log file errors I've reenabled all those system plugins. I can't see any difference in the user interface and I can't actually remember where gadgets used to live. I've had a look at the Confluence documentation and it seems like Gadgets are very limited, much more than I remember them. I can't see any where that end users can utilise anything related to "gadgets", even in the macro browser. Does anyone have any clues as to what it means to have gadgets enabled? Can I just relax now days?