Numbers are classified as even or odd based on whether they are divisible by 2 or not.
An even number is any integer that is divisible by 2 without leaving a remainder, such as 2, 4, 6, 8, 10, and so on.
On the other hand, an odd number is any integer that is not divisible by 2 without leaving a remainder, such as 1, 3, 5, 7, 9, and so on.