Can anyone explain this to me in a way that addresses what I'm experiencing? (As follows...) So, I am under the impression that "swap used" is when you use your HD as 'RAM' when you run out of actual RAM. Please stop me here if this is wrong. If that is true though, then I'm a bit confused, because on my Mac with 4GB RAM, using Mavericks, I have no swap used but I periodically check my available HD space, and it progressively decreases. I haven't been downloading anything, so I am near 100% certain it's coming from using it as memory. I am a bit concerned if this actually is true, because I would have hoped and expected that the revolutionary new memory management with the OS would prevent this from happening, whereas on all previous OSs on my mac, I've very rarely had memory written to the HD (I would monitor my RAM and close programs when needed to prevent the 'page outs' and 'swap' from occurring). Any insight would be great, thank you!