Most of the digital cameras have a rechargeable battery. Some have option for using dry cell also. That’s good, it helps if you are in a place with no electricity - trecking site for example. So think about it when buying a digi-cam.
Now the re-chargable batteries have a life continuously reducing on use. My infolithium used in Sony, showed a 30% reduction. There is a fix for this. Charge the battery fully and then do a rapid discharge - may be connect to a bulb of same voltage and high watts. You can also use the camera with flash rapidly to discharge the battery. When it is completely done, recharge the battery again fully. Do the discharge once more. Now on re-charging, you will find that the life has considerable increased.
So don’t worry if you face a decreased battery life.
Be careful when you discharge the battery externally. Don’t short circuit the terminals. It will damage the battery.
Best of luck.