Hi, this contraceptive pills has maximum efficacy. They prevent the ovulation and hence pregnancy. There are lot of advantages and disadvantages. Advantages being painless period, regular cycles, relatively less flow in case of women with menorrhagia. Disadvantages are bloating sensation, weight gain, breast tenderness. Even though OCPs prevent pregnancies they do not protect you against sexually transmitted diseases. Hence you might need a barrier contraception if you are concerned about them.