Possible Combinations 3 Digits How Many Different Combinations Of 3 Different English Letters Are Possible.?

How many different combinations of 3 different English letters are possible.? - possible combinations 3 digits

English letters A through Z, if I want to make a combination of 3 digits, for example. ABC, ZDE, QPR, etc., knowing full well that there are 26 English characters, how many different combinations are possible? Thank you.