TDEE refers to "Total Daily Energy Expenditure". In short, it refers to the daily calories (energy) your body burns on a day to day basis
Hence by calculating your TDEE aka Maintenance Calories, you will be able to identify the calories required to maintain your current weight, and to increase (or decrease) your caloric intake to build muscle (or burn fat).
Determine the amount of calories you need to maintain your current
Note: Do not use this
calculator if you are under the age of 18. The results then may differ from reality.
Note: This is the daily amount of calories you need to keep your current weight