Contraception is the name we give anything that tries to avoid pregnancy. This could be done either by attempting to stop a sperm from meeting an egg or by preventing a fertilized egg from implanting itself in the womb.
These days there are so many types of contraception available it can be a bit confusing to know what does what and how and why?
There are a lot of myths around how to avoid pregnancy, such as having sex standing up, having a bath afterwards, it being a girls first time and withdrawal. None of this will prevent pregnancy...
Withdrawal or taking a penis out before ejaculation is not a form of contraception, there is something called precum that is produced from the end of the penis before ejaculation. This precum may deliver around 80,000 sperm into the vagina. Be prepared for babies if you try this; it only takes one sperm to fertilize an egg. It is also very important to make sure this precum doesn't transfer to the vagina by touching with hands etc, it is possible (although not common) to make a baby without actually having sex!