As you may already know, contraceptives are methods or devices that are used to prevent pregnancy. These include pills, injections, implants, condoms, patches, vasectomy, etc. I am guessing when you asked this question you thought that contraceptives only refer to pills or injections! One addition to the list of contraceptives is abstinence or kuchill!
Remember, the primary goal of contraceptives is to prevent pregnancy, especially unplanned. You can imagine having to give birth to a baby that you are not ready for e.g. you don’t have enough money to feed and clothe the baby, you are still in school, man and woman are not yet married, etc. Some people opt to go for unsafe abortions from quarks (unqualified medical personnel) in backstreet clinics and because of this many women die annually. Very sad indeed! It is better to prevent such pregnancies until both the man and the woman are ready to bring a baby into the world. Taking care of a baby is not easy or cheap. It requires investing in time and money.
As scientists, we are motivated by problems that we observe in the world…then we think of possible solutions. As scientists, we can help solve this problem through coming up with better drugs or methods that are safe and effective. As you can see from the list of contraceptives, they are many. The choice of a contraceptive depends on a lot of things e.g. effectiveness, frequency (daily pill or annual injection), health status, age, etc. Some have side-effects, but you should know that before a drug/injection is approved for use in people very many tests are usually conducted to ensure that: 1. It is safe, and 2. The side effects, if present, can occur in very few people. But remember, even food that you eat can have side effects in your body!
However, scientists continue working hard to reduce the side effects. We encourage people to use contraceptives as there are massive benefits: prevent unplanned pregnancies that may lead to unsafe abortions or suffering of mother and child, prevent sexually transmitted infections (e.g. syphillis), etc. Since you are in school, I will advocate for kuchill and you will have NO unplanned pregnancy, NO unsafe abortion, MORE concentration in school work, BETTER future. I hope you work hard and become a scientist to help us make the world a better place!
The main reason why people use contraceptives is to reduce the chances of getting pregnant, that is for family planning purposes. With new methods of contraceptives the side effects are very minimal and can be managed. Scientist and even governments encourage family planning in order to manage population growth. Populations are managed to ensure the resources of the country can sustain the population. Also families with few resources are better of with fewer kids to be able to provide them with their needs.