MemInfo is a tiny tool which can help you find out more about how your PC RAM is being used.
At its simplest, the program can just leave an icon in your system tray to highlight your current RAM consumption (you might have it display the percentage used, for instance). This is clearly very basic, but it's still enough to be useful, as you'll soon notice if, say, your free RAM is dropping over time, or falls particularly when you're running a certain application.
Simply hovering your mouse cursor over the MemInfo icon will reveal more details, as the program displays the precise amount of RAM available and used, as well as details on your system's paging file.
If it looks like your free RAM is falling for some reason, right-click the icon and MemInfo will show you more statistics, including a list of the ten processes which are currently using the most memory. Clicking on any of these will display more details on the program, as well as giving you options to free up RAM from that process, or close it down entirely.
There's even a "memory defragmenter" option, which the authors claim may "speed up your computer by maximizing the available free memory", although for most people we suspect it probably won't make any difference at all.
MemInfo is highly configurable, too, so if you don't like some aspect of the program, just right-click its system tray icon, click Settings and start browsing: there's probably a tweak there which will allow you to change things.
And while MemInfo will of course use some RAM itself, fortunately it's extremely lightweight. On our test PC it consumed less than 1MB RAM (and often much less), so should run happily in the background just about anywhere.