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What does "key" mean in programming?
key is one of the most common terms in software development. This guide explains what it means, how it is used in practice, and why it matters, with real examples from the developer world.
Definition
The identifier used to store and retrieve a value in a dictionary, hash map, or object. Keys must be unique within a given data structure. In databases, a key uniquely identifies a row.
Example
"Use the user ID as the key so you can look up any user in O(1) time."
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