What information is encoded in a bitcoin QR code?

As a finance and cryptocurrency practitioner, I'm often curious about the underlying technologies. When it comes to bitcoin QR codes, I'm interested in understanding what specific information is encoded within them. After all, QR codes have become a ubiquitous way to quickly transfer data, and in the context of cryptocurrencies, they play a crucial role in facilitating secure and convenient transactions. So, what exactly is encoded in a bitcoin QR code? Is it just the recipient's wallet address? Or does it include additional details like the transaction amount, payment notes, or even a timestamp? Understanding the specifics of what's encoded in these QR codes could provide valuable insights into how they are being utilized in the crypto landscape and how they can be further optimized for efficiency and security.