The greatest common factor (GCF) of 8 and 12 is 4. To find the GCF of 8 and 12, we need to factor each number and choose the greatest factor that exactly divides both 8 and 12 without any remainder. The factors of 8 are 1, 2, 4, and 8, while the factors of 12 are 1, 2, 3, 4, 6, and 12. The common factors of 8 and 12 are 1, 2, and 4, and the greatest of these is 4, which is the GCF of 8 and 12.