What is the ICP Internet Computer protocol?

What is the ICP Internet Computer protocol? Could you explain it to me in a simplified way? I'm not quite familiar with the intricacies of cryptocurrency and finance, so I'd appreciate it if you could break it down for me. How does it work? What are its key features? And what are the potential benefits or use cases of ICP in today's digital world? Is it safe and secure to use? Could you also provide any insights into its future prospects or potential challenges?