What is mAh? What is the relation with battery?

In simple words, mAh means the capacity of energy a battery can store. mAh means milliAmp hour or Ampere hour. Here watt-hour (wh) is the electric energy. 

Watt-Hour = Voltage x Ampere-Hour

This is the formula to measure it. Whenever people go to a shop to buy a any device which runs on a battery or a power bank, they often asks for the battery capacity. The bigger the no., more the battery time.

Suppose you are a boy or a girl, you slept for 8 hrs yesterday night which charged your body. and now your mom asked you to go to the market and bring some potatoes. You will dress up and will run to shop. You will ask the shopkeeper to give 1 Kg potatoes. Returning home with that heavy bag of potatoes. Then, you will take rest.

Now, 

the 8 hrs sleep = you phone got charged [2000 mAh]

Dress up = you check out notifications of your phone [10 mAh]

Run to shop = check out your best friends message and replying to it [50 mAh]

1kg potatoes = playing games to check out clash of clans or candy crush live recharge [75 mAh]

Returning home = Cleaning the opened apps by swiping each of them from the recents panel [1 mAh]

Rest = You locked your phone [Saving your battery]

Now out of 2000 mAh of your phone, 136 mAh you lost, means only 1864 mAh is left. This is how your phones mAh gets reduced.

Your phones battery can also gets reduced if you dont clean up junk file and remove apps from recents panel. 

Special Tips to save battery : 

1) Do clean junk files regularly. Use es file explorer to clean junk files.

2) Try to keep less apps. If your phone have root access, then freeze those apps you are not using currently using app freezer. Download it from here.

3) If your phone has a memory card support then do move your files from internal memory to your memory card. Try to keep internal memory free as much as you can. 

4) Don't use any type of ram cleaner, battery saver or any type of antivirus. These apps also eats lots of ram, which reduces the battery life by running till you shut down your device, Android users, please note : your phone is based on linux operating system which doesn't get infected from any kind of virus. To check for viruses in your sd card, you can eject it and scan it through your PC antivirus application.