In linguistics, context is the parts of an utterance surrounding a unit and which may affect both its meaning and its grammatical contribution. A context-free grammar is one where the rules apply regardless of context; a context-sensitive grammar is one where this is not so. Context also refers to the wider situation, either of speaker or of the surroundings, that may play a part in determining the significance of a saying. Sometimes the term co-text is used for the narrow purely linguistic context.