Green Daily

When you put your computer into sleep mode (which is often the default setting when you close your laptop lid, for example), your PC still draws some energy from the battery or wall outlet. That's because all of your data is being saved to RAM, which requires power. If the power goes away, so does all of the data stored in RAM. Hibernate mode, on the other hand, saves all of your information to the hard disk, which does not need power. So if you put your computer into hibernate mode when you're not using it, you can save all of your running programs just as if you were in sleep mode. And your computer will use almost no energy at all, just as if you had turned it off altogether.

The reason people don't use hibernate more often is because it eats up hard drive space and it takes longer to resume from hibernation than from sleep mode. But there's really no reason anyone should need a plastic dongle which actually draws power from your USB port in order to save electricity. And did I mention that the Ecobutton lights up? Because that's necessary.

[via Environmental Leader]