In linguistics and grammar, affirmation (abbreviated AFF) and negation (NEG) are ways in which grammar encodes positive and negative polarity into verb phrases, clauses, or other utterances. An affirmative (positive) form is used to express the validity or truth of a basic assertion, while a negative form expresses its falsity. For example, the affirmative sentence "Joe is here" asserts that it is true that Joe is currently located near the speaker. Conversely, the negative sentence "Joe is not here" asserts that it is not true that Joe is currently located near the speaker.
The grammatical category associated with affirmatives and negatives is called polarity. This means that a clause, sentence, verb phrase, etc. may be said to have either affirmative or negative polarity (its polarity may be either affirmative or negative). Affirmative is typically the unmarked polarity, whereas a negative statement is marked in some way. Negative polarity can be indicated by negating words or particles such as the English not, or the Japanese affix -nai, or by other means, which reverses the meaning of the predicate. The process of converting affirmative to negative is called negation – the grammatical rules for negation vary from language to language, and a given language may have multiple methods of negation.
Affirmative and negative responses (specifically, though not exclusively, to questions) are often expressed using particles or words such as yes and no, where yes is the affirmative, or positive particle, and no is the negation, or negative particle.