Decoding is the process of translating print into speech by rapidly matching a letter or combination of letters (graphemes) to their sounds (phonemes) and recognizing the patterns that make syllables and words. It is a key skill for learning to read and is the foundation on which all other reading instruction builds. Decoding involves a series of smaller skills, such as taking apart the sounds in words, known as "segmenting," and then blending them together. It also uses knowledge of letter and sound relationships, and the ability to use that knowledge to identify written words and understand what they mean. Decoding takes place in the part of the brain that handles language processing, and with enough practice, the brain uses the decoding skills automatically.

In semiotics, decoding is the process of interpreting a message sent by an addresser (sender) to an addressee (receiver) ). The complementary process of creating a message for transmission to an addressee is called encoding).