The pill or oral contraception are tablets which generally contain a combination of two hormones: oestrogens and progesterone. It is then called the "combined pill". There are many pills depending on their composition and the dose of hormones they contain.
Other contraceptive pills only contain one hormone, progesterone. These are called the "progestogen pills" and are taken continuously without being stopped.
The pill acts at different levels, blocking ovulation, thinning the internal wall of the uterus (endometrium), altering the consistency of cervical mucus (secreted by the cervix) that, becomes thick and prevents spermatozoa crossing).
The pill is very effective if it is taken very regularly. Forgetting a single pill can make the method fail. In order not to forget, try to take the pill at the same time as you do an everyday activity (brushing teeth, breakfast, etc.).