In linguistics, grammatical number is a feature of nouns, pronouns, adjectives and verb agreement that expresses count distinctions (such as "one", "two" or "three or more"). English and other languages present number categories of singular or plural, both of which are cited by using the hash sign (#) or by the numero signs "No." and "Nos." respectively. Some languages also have a dual, trial and paucal number or other arrangements. The word "number" is also used in linguistics to describe the distinction between certain grammatical aspects that indicate the number of times an event occurs, such as the semelfactive aspect, the iterative aspect, etc. For that use of the term, see "Grammatical aspect". Most languages of the world have formal means to express differences of number. One widespread distinction, found in English and many other languages, involves a simple two-way number contrast between singular and plural (car/cars, child/children, etc.). Discussion of other more elaborate systems of number appears below. Grammatical number is a morphological category characterized by the expression of quantity through inflection or agreement. As an example, consider the English sentences below: That apple on the table is fresh. Those two apples on the table are fresh. The number of apples is marked on the noun—"apple" singular number (one item) vs. "apples" plural number (more than one item)—on the demonstrative, "that/those", and on the verb, "is/are". In the second sentence, all this information is redundant, since quantity is already indicated by the numeral "two". A language has grammatical number when its nouns are subdivided into morphological classes according to the quantity they express, such that: Every noun belongs to a unique number class (nouns are partitioned into disjoint classes by number). Noun modifiers (such as adjectives) and verbs may also have different forms for each number class and be inflected to match the number of the nouns to which they refer (number is an agreement category).