A lock is a device that keeps doors, boxes, or other things closed and secure, usually opened with a key or code. As a verb, it means to fasten something so it cannot be opened or used freely.
It comes from Old English “loc,” meaning “fastening” or “barrier,” related to similar Germanic words. The basic idea of securing or closing something has stayed constant.
Locks create a tiny universe of trust: you trust that your key is unique enough to keep others out. Modern digital locks, like passwords and encryption, follow the same ancient idea—only those with the right “key” may enter.
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