Divisibility is a mathematical concept that determines whether one number can be divided by another without leaving a remainder. For example, if you divide 10 by 2, the result is 5, and there is no remainder, so we say that 10 is divisible by 2. Certain rules can help identify divisibility for specific numbers. For instance, a number is divisible by 3 if the sum of its digits is divisible by 3. Similarly, a number is divisible by 5 if it ends in 0 or 5. These rules simplify the process of checking divisibility.