An abortion is when the pregnancy is ended so that it does not result in the birth of a child. Sometimes this is called 'termination of pregnancy'.
The pregnancy is removed from the womb, either by taking pills (medical abortion) which involves taking medicines to cause a miscarriage or by surgery (surgical abortion) where the pregnancy is removed from the womb. Most abortions can be provided on a day care basis which means you do not need to stay at a clinic overnight.