The internal database engine of wallet.dat depends entirely on when the file was created. Modern versions of Bitcoin Core have transitioned away from historical formats to improve software maintenance and data reliability. Berkeley DB (Legacy) vs. SQLite (Modern)
The file organizes cryptographic and operational data using specific key-value prefixes: Key Type / Prefix Stored Data & Purpose tx Bitcoin Core Wallet.dat
This is why the phrase is so central to Bitcoin philosophy. The internal database engine of wallet
Keep backups on at least two different physical devices (e.g., two encrypted USB drives) [3, 5]. two encrypted USB drives) [3
When you open Bitcoin Core, the software loads your wallet.dat from the data directory (usually %APPDATA%\Bitcoin\ on Windows, ~/Library/Application Support/Bitcoin/ on macOS, or ~/.bitcoin/ on Linux).