The idea

A text model scores possible next tokens. A token is a piece of text. The system then chooses one and repeats the process. Some methods choose the highest score. Others allow a choice from several likely tokens.

What to check

That is one reason the same question can get different answers. Settings can narrow the choices, but a low temperature does not guarantee the same result on every run. A repeated answer can still be wrong.

Some models spend extra work before answering. This may help with a hard task. It does not make the result true. A written chain of steps is also output that needs checking.