If you've ever opened up your Activity Monitor and looked at the System Memory tab, you've no doubt seen something similar to the above. But if you're like me, you've often wondered just what the labels mean. Just what is wired memory, anyway? Well Alex at Bits about Bytes has a nice little article explaining just what those labels mean, how different applications (particularly virtualization tools) affect memory usage, and how to figure out if you need to add RAM to your system. Oh yeah, and wired memory turns out to be memory "used by the OS [which] is pretty much untouchable. Another application can't 'borrow' wired memory." Good stuff.