In Bitcoin technology, several particularly interesting designs:

PoW: Hard to solve, easy to verify.
Miners may need to compute trillions of hashes to find a block, but the entire network can verify it with a single hash. It's like spending a day solving a math problem but only a minute to check the answer.

Difficulty adjustment: Price goes up, supply does not.
The difficulty automatically adjusts every 2016 blocks. The higher the hash rate, the higher the difficulty, and blocks still occur roughly every 10 minutes. If gold rises in price, more is mined. If Bitcoin rises in price, the network only becomes more secure, without increasing supply.

Script: Deliberately not too smart.
Bitcoin scripts have no loops and are not Turing-complete, so there are no infinite loops, logic bombs, or similar issues. It chose security over functionality.

UTXO: Like cash change.
Your wallet is not a balance but a collection of "coins" (UTXOs). When paying, they are automatically combined, and change is returned. This makes tracking easier and is better suited for parallel processing.

The genesis block message.
Satoshi Nakamoto embedded the headline of The Times in the first block: "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks."
This serves as both a timestamp and a declaration against the fiat currency system at the birth of Bitcoin.

Full nodes are the true arbiters.
Miners are responsible for producing blocks, but it is the users running full nodes who truly determine which blocks are valid. Miners cannot arbitrarily change the rules; otherwise, users simply refuse to acknowledge them.

The first implementation of digital scarcity.
Pictures and files can be copied infinitely, but Bitcoin made digital assets truly unique: when you send it to someone else, you no longer have it.

"Bitcoin is great not because it solved the payment problem, but because it solved the issuance problem — no one can inflate it, no one can control it."

Many people, after studying it in depth, find that the most remarkable thing about Bitcoin is not its price, but these seemingly simple yet interconnected technical designs.