After the performance and features of the cell phone, nothing is more important than the life of the cellular phone battery. The longer the battery life, the more talking before it needs a recharge. Sometimes your cellular phone battery will wear out. It will not hold its charge as long and your talk time will be noticeably diminished. At that point it's time to get a new battery. Make sure you get the correct battery for your cell phone model. If it's the wrong one, it will not fit.
There are actually three different types of materials that make a cellular phone battery. The metals are nickel metal hydride, nickel cadmium and lithium ion. The lithium ion cellular phone battery is the most common because it has the longest battery life, about 3 to 5 hours of talk time. They can be recharged around 200 times before you need to purchase a new one. When you replace your cellular phone battery, make sure to dispose of the old one at the correct hazardous waste place or at a store that will accept old batteries to be disposed.
The cellular phone battery should be stored at room temperature as extremes in heat and cold can damage it. Wait till the battery has completely run dry before recharging. These batteries have a memory, which means that if it normally would have 2 hours of talk time, and you recharged at 1 h hours of talk time, then that's the max charging the battery will accept now. You'll be stuck at 1 h hours of talk time. Read the instructions on charging and recharging the cellular phone battery and make sure you do not overcharge as well.
When purchasing a replacement cellular phone battery, I would suggest buying only OEM (original equipment manufacturer). There have been problems with third party cell phone batteries blowing up. They were sold and made specifically for a certain phone model, but if the battery was manufactured incorrectly it will overheat and blow up during charging. OEM batteries are more expensive, but I think they are well worth the cost.
You can charge up your cellular phone battery with an AC adapter (desktop charger) or car adapter charger. You will generally have to buy the car adapter separately but but I have found it to be invaluable on trips. You can buy the car charger from the same store that you bought the cell phone. Make sure you check the make and model number so that you buy the correct one for your phone.