What is the machine that gives you oxygen?

Could you elaborate on the machine that provides oxygen? Specifically, I'm interested in understanding its basic functionality, operation, and any relevant technological advancements that have enabled it to become an essential part of modern life. What are the key components of this machine, and how does it convert air or other substances into breathable oxygen? Additionally, what are some potential challenges or limitations in its use, and how are researchers and engineers addressing them to improve its efficiency and reliability? I'm keen to gain a comprehensive understanding of this machine and its role in sustaining human life.