System monitoring is an important aspect of any more-or-less advanced Linux user, because there comes a time when you want to know what is taking precious resources or simply how much it does take. And despite what some people think, this is not applicable only to server systems. Desktop applications go haywire too, and you find your system slowed down to a crawl because some "rogue" app decided to eat up all your memory. For enterprise users there are lots of potent free or commercial solutions for monitoring, but for the old-school Linux user and/or someone that prefers to keep it simple, there is always top(1).If you're somewhat familiar with the command line, you will probably benefit more from this article, but that doesn't mean GUI-centric users won't.