What is the basics of bitcoins & blockchains?

Could you please elaborate on the fundamentals of bitcoins and blockchains? I'm particularly interested in understanding the CORE principles that underpin these technologies. Could you start by explaining what bitcoins are, how they function as a decentralized digital currency, and how transactions are verified without a central authority? Then, could you go on to discuss blockchains - what they are, how they serve as the underlying technology for bitcoins, and how they ensure the security and integrity of transactions? I'm also curious to know about the potential applications of blockchains beyond just bitcoins. Thank you for your time and expertise in this area.