Losing gigs from unknown source. Why?

On my hp 15 laptop i have almost 500 gigs but its only 380 something left over the last couple of days i notice i have been slowly losing 1 gig at a time like yesterday it 386 today its 385. I do not download really much so I'm wondering where is my space going to. Has anyone been having this too?

Check your browser cache some have no limit and just keep growing firefox now installs 256 folders on your hard drive for cache files

Cache files, temp files, virtual memory… There's a million things that might be using up free HD space, but until you get down to 10% or so it really doesn't matter. Give it a restart and see what happens.