AO battery losing charge

Why does the battery lose charge when its turned off? Is there something I should read to explain the battery tech info? Is it important to charge the battery to full capacity three times (after letting it go down low).

 

In many cases with a device that has a digital switch, there is a little power still going through it if nothing else, just to keep track of the switch so it will know when someone has turned the computer on. I don't think any modern notebooks have physical switches anymore, so most any of them will loose some charge, the longer it sits, the less charge it will have when you turn it back on.

I suppose you could remove the battery, and keep more of a charge, but many newer batteries even have circuitry inside of them to keep track of the charge so they won't overcharge, or will shut down when it gets to low, so I suppose it may still loose some charge even unplugged. Though it should take longer than plugged in.