Most languages have ways to express differences of number.
- That apple on the table is fresh.
- Those two apples on the table are fresh.
Common categories of grammatical number are singular (one) or plural (not one). Some languages, also have a notion of dual, for two, or paucal for "a few". Some languages (for example Chinese) do not have the concept of grammatical number. In these languages, numbers (or other quantifiers) are used, if necessary. Finally, there may be words which only have one form, or which are not countable.
- Greenberg, Joseph H 1972. Numeral classifiers and substantival number: problems in the genesis of a linguistic type. Working Papers on Language Universals 9, Stanford University, pp. 1–39.
- Laycock, Henry 2005. Mass nouns, count nouns and non-count nouns. Encyclopedia of Language and Linguistics. Oxford: Elsevier.
- "What is Number?", Dictionary of Linguistic Terms, SIL.