Assisted suicide is when somebody who wants to commit suicide (wants to die) is helped to do this by someone else. Normally, people who ask for assisted suicide are very ill and in a lot of pain, so they want someone to help them to die, for example by being given access to drugs which will kill them. Some people prefer the terms aid in dying or death with dignity to describe assisted suicide. The term euthanasia is sometimes used, although euthanasia is generally regarded as different to assisted suicide, as it involves causing a person to die rather than helping them to kill themselves.
The law about this varies a lot in different countries. In Belgium, the Netherlands, Switzerland and in three American states it is legal to help someone to die in these circumstances. However, in many countries it is not allowed, and the person who helps someone to die may be arrested and sent to prison.
Some people who are very ill and want to die may go to these countries, such as Switzerland, in order to end their life.