Can you explain Descartes' dream argument and how it relates to the nature of reality?

Descartes' dream argument suggests that we can never be certain if we are truly awake or dreaming because our senses can deceive us. This challenges our understanding of reality, as it raises doubts about the reliability of our perceptions. It highlights the idea that what we perceive as real may not actually be so, leading to questions about the nature of reality and the limitations of human knowledge.