Batteries run just about any device you can think of, be it your phone, iPod, or computer. Taking a few steps in how you use your devices can lengthen you battery life by a lot! Some good suggestions would be to:
-Lower your brightness
-Turn off automatic updates and background sync's such as Facebook and twitter
-Have shorter screen timeouts
-Keep your device plugged in while using it if your not going anywhere
-Take off the back to charging phones to reduce heat (heat is VERY bad!!!)
I know that my phone which is an Android that it's recommended that once a month I let my battery fall below 20% then charge it completely back up, which in a sense refreshes the battery pack and is beneficial to battery life.
So don't be oblivious and keep wasting all your battery life, let your device have a break every now and then and keep it fresh!