Is it illegal to commit suicide? If so I don't understand why. Illegality is irrelevant at that point right?

Ridiculously, it used to be illegal in most of the western world to commit suicide. People who succeeded were given undignified burials. And people who didn't succeed were condemned to death. And then given undignified burials. It was a crime in Ireland until 1993! In the United States, a few states still describe attempted suicide as a felony, but there is no penalty and I've never heard of anyone being prosecuted.

What the law does is to encourage people who attempt suicide to be sure to finish the job.

In what country or state? Remember that their laws are all different.

In the few places where it is illegal, it's usually because the majority religion is against it. Obviously you can't prosecute a successful suicide, but you CAN prosecute an unsuccessful one as an attempted suicide. That was, for example, the position in the UK until 1961 - it was illegal at common law probably because Christianity says it's a sin.

But most places have long since realised that if you attempt suicide and fail, prison is the last thing you need! What you NEED is help! Therefore suicide is not illegal, and that means attempted suicide isn't either.

No where in the US, or about 98% of the rest of the world, is suicide (or even attempted suicide) illegal. You will not be arrested for it, will not face criminal charges, and will not have a fine or sentence to serve. What you will likely get is a mandatory hold in a psychiatric facility for observation, but that's about it. Why that? Because suicide is a sign of a mental health problem.

If you commit any crimes in your act of trying to kill yourself, you could be charged with THOSE crimes (assuming the suicide attempt was unsuccessful), but not for the suicide itself. For example, if you decide to kill yourself by driving your car at high speeds into another car, and you kill the other driver, you could be charged with murder.

Nothing if you succeed, but many suicides don't. The laws are written so that the attempted suicide can receive mental health help whether they want it or not.

Its legal in the UK, but illegal to assist someone to commit suicide.

suicide is not illegal. but obviously it is not encouraged

It gives them something to hold you on, without proving you're mentally ill.

It was illegal in britain until 1961 to attempt suicide, not to commit suicide!

In most countries it's illegal. Quite a lot of suicides are unsuccessful and so leave that person open to criminal charges, which could be jail time or being committed to a psychiatric hospital.