Hash
DataDefinition
A hash (or digest) is a fixed-length output produced by a hash function from any-length input. Hash functions are deterministic (same input → same hash), one-way (cannot reverse), and produce drastically different outputs for similar inputs (avalanche effect). Used for data integrity and passwords.
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Base64
Base64 is a binary-to-text encoding scheme that represents binary data using 64 printable ASCII characters (A-Z, a-z, 0-9, +, /). It increases data size by ~33% but allows binary data to be safely transmitted over text-only channels like email and URLs.
URL Encoding
URL encoding (percent-encoding) converts characters that are not allowed in URLs into a safe format by replacing them with a % followed by two hexadecimal digits. Spaces become %20 or +, special characters like & and = are encoded when used in query parameters.
UTF-8
UTF-8 is a variable-length character encoding for Unicode. It represents each character using 1 to 4 bytes and is the dominant encoding on the web (used by ~98% of websites). UTF-8 is backward compatible with ASCII — the first 128 characters use one byte each.
ASCII
ASCII (American Standard Code for Information Interchange) is a character encoding standard that assigns numbers 0-127 to characters: 0-31 are control characters, 32-127 are printable characters (letters, digits, punctuation). ASCII is the basis for UTF-8 and most modern text encodings.