1. Bitcoin Transactions:
   • Transactions are made when users send Bitcoin to one another. Each transaction is broadcast to the Bitcoin network.
   • These transactions wait in the mempool (a temporary holding area) until they are included in a block by a miner.
2. Blocks:
   • A block is essentially a "page" in the Bitcoin ledger that contains a list of verified transactions.
   • Each block references the previous block through a cryptographic link (the hash of the previous block), forming a chain — the blockchain — which is the entire history of Bitcoin transactions.
3. Miners' Role:
   • Miners compete to create the next block by solving a cryptographic puzzle (Proof-of-Work).
   • The first miner to solve the puzzle adds the new block to the blockchain and broadcasts it to the network.
   • As a reward, the miner earns the block reward (newly minted Bitcoin) and transaction fees from the transactions in the block.
4. Nodes' Role:
   • Full nodes receive the newly mined block and validate it to ensure it follows Bitcoin's rules (e.g., no double-spending, proper block structure, valid transactions).
   • Nodes store a full copy of the blockchain and enforce consensus rules. They reject any invalid blocks or transactions.
   • By doing so, nodes ensure the network remains secure and decentralized. There are thousands of Bitcoin nodes around the world, many operated by individuals, businesses, and institutions making it impossible for anyone to change Bitcoin without the majority of these nodes agreeing to the change.
   • Bitcoin Nodes in Space:
     • Blockstream Satellite: Blockstream has launched satellites into orbit that broadcast the Bitcoin blockchain to the entire Earth. This allows users to access Bitcoin without an internet connection, ensuring resilience during internet outages or censorship. Users only need a simple satellite dish and receiver to connect.
   • EMP-Resistant Nodes:
     • Faraday Cage Nodes: While specific examples of individual nodes aren't publicly advertised for security reasons, enthusiasts and businesses have built Bitcoin nodes inside Faraday cages to protect against EMPs. For instance, some survivalist communities incorporate EMP-hardened Bitcoin nodes as part of their disaster preparedness setups.
   • Bunker Nodes:
     • The Swiss Fort Knox: Several companies operate Bitcoin nodes in heavily fortified data centers, such as the ones buried deep in Swiss mountains. These facilities are designed to withstand natural disasters, EMPs, and even military attacks.
     • The Underground Data Center in Stockholm: Located in a former nuclear bunker, this facility houses Bitcoin nodes and other critical infrastructure, designed to survive extreme conditions.
   • Decentralized Distribution:
     • Home and Business Nodes: Many individuals run Bitcoin nodes in their homes or offices worldwide. While not as protected as the examples above, the sheer number of nodes (tens of thousands globally) ensures the network continues to function even if some go offline.
5. These examples highlight the extraordinary measures taken by Bitcoin users and organizations to ensure the network remains operational under any circumstances.
6. Decentralized Ledger:
   • The blockchain, stored on nodes worldwide, acts as the official, tamper-proof record of Bitcoin's transaction history.
   • This decentralized ledger prevents any single entity from altering the history or rules of Bitcoin.

Key Points to Remember:

• Miners: Create and propose new blocks by expending computational power.
• Nodes: Validate and store the blockchain, ensuring it adheres to Bitcoin’s consensus rules.
• Blockchain: A chronological and cryptographically secure ledger that keeps track of all Bitcoin transactions.