When you are using your battery have you ever noticed that the amount of time you have until the charge runs out often drastically varies? The reason your battery sometimes drains quickly is usually due to one of two reasons: 1) Sometimes an app you are not even using will sit in the background constantly using 100% of one of your processor cores. Having a Flash application open in one of your tabs is a common cause of this. 2) As you may know your MacBook Pro actually came with two graphics cards. One that uses little power, and one that is much more powerful but uses significantly more power as well. If you have Lion and a more recent MacBook Pro your OS will automatically switch between the two, but sometimes you will have an app or a webpage open which holds the power hungry graphics card open unnecessarily draining your battery. Battery Guru will monitor and present realtime information on exactly how many milliamps your battery is using at any given moment and display it in your menu bar. This way you can keep an eye on the number, and if it gets too high you know that something is draining it faster than it should be and you can investigate and close the offending page or application if you're not using it. It secondary function is to provide information that you do not usually have access to. It will show you: - The current capacity that your battery can now hold compared to when it was new - The number of times your battery has been discharged and recharged - The date your battery was manufactured - The exact temperature of your battery - The current charge of your battery as a more exact percentage than provided by the operating system As your computer comes with a "Smart Battery" your battery actually already knows this information and holds it internally. Battery Guru is your means of accessing it, allowing you to monitor the current state of your battery and be more aware of what is going on in your system.