Here's a few things you should know:
1)Browsers take up a crap ton of ram. If you don't want them to take up too much RAM, don't open up 12 windows of the same task at once if you don't need so much windows. I advise you to open up tabs instead of windows.
2)RAM is a storage place for all processes that you're hosting. CPU sends processes to the RAM, and that's where stuff happens. In other words, it's very important.
3)The amount of RAM doesn't have anything to do with the amount of RAM being used. It doesn't mean that 32 gigs or 128 gigs means lower host processes.
4)With what you said, "How I have 16 RAM" I'm pretty sure you're asking why it's taking up 2000 mb of memory. Don't worry about that, MB and GB are two different things.