What is Descartes evil genius argument?

Descartes uses the evil genius argument to get everything except what he can be sure is true off of the table.

He asserts that there is an evil genius as powerful as God that is deceiving him about absolutely everything. He cannot be certain of any of his thoughts in such a scenario. He cannot be perfectly certain that this evil genius does not exist. As a result, it is impossible to fully trust anything in terms of senses, memories, thoughts, or beliefs.