This is not a post for people who know a lot about computers. I definitely am not one of those people.
Case in point: I only recently realized that when I simply close my laptop when it's not in use, the power will still drain out. Only then did it occur to me that the computer still uses power when it's closed but not shut down (this seems stupidly obvious now, but some things take a while to sink in).
Then I noticed that when I go to shut down my laptop, there is a little hibernate button whose purpose I've never cared to wonder about until now. Turns out, it's quite handy.
If you're like me and don't know the difference between sleep, hibernate, and shut down modes, let me help you out. It's pretty simple.
Your computer uses less power than when it's open and running (duh) but because you've still got open applications and work you may not have saved, it's still using power to keep all of that available to you while it's closed, so that it will still be there when you open it back up again. When you open it back up, it will boot up quickly, and you can resume your work where you left off.
Best use: when you'll be away from the computer for a short time, like going out to grab lunch.
If you put your computer into hibernate mode, it will use much less power than when it's in sleep mode. That's because your computer will save your current state (all the stuff you have open and running) to your hard drive before it goes into hibernate mode, so that it doesn't have to use as much power to keep all of that going. When you wake it from hibernate, which will take a little longer than waking from sleep mode (but not as long as waking from shut down mode) you can still pick up where you left off with your work, but you'll have used much less power than if you simply put your computer to sleep.
Best use: when you'll be away from the computer for a medium amount of time, like when you take the afternoon off to go for a bike ride.
SHUT DOWN MODE
In shut down mode, your computer uses no power, though shutting down does require you to save all the work you've done and fully close out of your programs. It will take longer to boot up from shut down mode than hibernate mode, but you'll have saved energy by giving your computer a rest. Also, it's generally a good idea to shut down your computer every once in a while, so that your system can update and refresh itself.
Best use: when you'll be away from your computer a longer time, like when you're done for the evening and won't come back to your work until morning.
Remember, even when your computer is shut down, it can still leech power if it's plugged in. So make sure to unplug your computer when it's not in use, or keep it plugged into a power strip with an on/off switch to keep the energy vampires at bay.