# Code ## Links (Wikipedia order) <!-- injected from _registry/childlinks/Code.json (2026-07-30T02:09:12Z) --> `-30-` · `ADDML` · `ASCII` · `Acronym` · `Algebraic_geometry_code` · [[Algorithm]] · `Amino_acid` · `Asemic_writing` · `BCH_code` · `Bag_tag` · `Binary_Golay_code` · `Biology` · `Bit` · `Black_Chamber` · `Block_code` · `Braille` · `Brevity_code` · `Byte` · `CJK_characters` · `Character_(computing)` · `Character_encoding` · `Chess_notation` · `Cipher` · `Code_(cryptography)` · `Code_(disambiguation)` · `Code_(semiotics)` · `Code_01_Bad_Girl` · `Code_02_Pretty_Pretty` · `Codec` · `Coding_theory` · `Cognition` · `Commercial_code_(communications)` · `Communication` · [[Communication_channel]] · `Communication_source` · [[Computer_science]] · `Concatenation` · `Cornet` · `Coupon` · `Cultural_code` · `DNA` · [[Data_compression]] · `Data_processing` · `Decoding_methods` · `Digital-to-analog_converter` · [[Digital_signal_processing]] · `Electronic_color_code` · `Equipment_codes` · [[Error_detection_and_correction]] · `Espionage` · `Flag_semaphore` · `Gene` · `Genetic_code` · `Geocode` · `Gesture` · `Gödel_numbering` · `Hamming_code` · `Herbert_Yardley` · `History_of_cryptography` · `Homomorphism` · `Huffman_coding` · `ISBN` · [[Information]] · [[Information_theory]] · `Internet` · `Journalism` · `Language` · `Language_of_flowers` · `Length` · `Letter_(alphabet)` · `Lookup_table` · `Low-density_parity-check_code` · `Marketing` · `Markup_language` · `Mathematical_notation` · `Mathematics` · `Messenger_RNA` · `Morse_code` · `Music` · `NTSC` · `Natural_language` · `Natural_number` · `Neuron` · `PAL` · `Parsing` · `Phonics` · `Plain_language` · `Postal_code` · `Protein` · `Quantum_error_correction` · `Reed–Muller_code` · `Resistor` · `SECAM` · `Secrecy` · `Semantics_encoding` · `Semaphore` · `Semiotics` · `Sheet_music` · `Sign_language` · `Space–time_code` · `Speech` · `Station_code` · `Stop_codon` · `String_(computer_science)` · `Symbol` · `Telegraphy` · `Text_Encoding_Initiative` · `Time` · `Turbo_code` · `UMTS` · `UTF-8` · `Unicode` · `Universal_language` · `Visual_system` · [[Wayback_Machine]] · `Wide_character` · `Word` · `Writing` · `Writing_system` · `ZIP_Code` > Signal Processing concept · part of the Signal Processing Portal · movement V · !74 記号 kigō.svg <!-- RENDER-THUMB:START --> !480 *Rendered from the live microsim (▶ motion).* <!-- RENDER-THUMB:END --> ## See it next [](Codec) *→ Codec* <!-- VISUAL-LINK:END --> --- Back to Signal Processing Portal · the room · Semiotic gateway ## What it is A code is a rule that converts information — a source symbol, message, or signal — into another form, typically a sequence of symbols drawn from a fixed alphabet, so that it can be stored, transmitted, or processed. ## How it works / why it matters In information and communication theory a code is a mapping from source symbols to codewords: *source codes* (like Huffman or arithmetic coding) minimize the average length of the representation to approach the entropy limit, while *channel codes* add structured redundancy so errors can be caught or repaired. A code may be fixed-length or variable-length, and desirable properties include being uniquely decodable and, ideally, prefix-free (instantaneously decodable). Codes are the foundation on which both compression and reliable transmission are built. ## Signs & universals Instantiates encoding and entropy — a code is the concrete mapping that realizes encoding, and its efficiency is bounded by entropy. ## Related The general notion underlying Codec, [[Data_compression]], and [[Error_detection_and_correction]]. Specific coding families appear in [[Speech_coding]], Video coding, and Forward error correction. <!-- VISUAL-LINK:START --> ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Code) : [Wikitube](https://en.wikitube.io/wiki/Code) ## Previous hub tags Tree parent: [[Information_theory]]. Legacy hubs: none. --- *Sources: 1 legacy note. Minted wave 1, 2026-07-30 (v1.6 order).*