The modern Chinese varieties make frequent use of what are called classifiers or measure words. One of the basic uses of classifiers is in phrases in which a noun is qualified by a numeral. When a phrase such as "one person" or "three books" is translated into Chinese, it is normally necessary to insert an appropriate classifier between the numeral and the noun. For example, in Standard Mandarin, the first of these phrases would be 一个人 yí gè rén, where yī means "one",rén means "person", and gè is the required classifier. There are also other grammatical contexts in which classifiers are used, including after the demonstratives 这 (這) zhè ("this") and 那 nà ("that"); however, when a noun stands alone without any such qualifier, no classifier is needed. There are also various other uses of classifiers: for example, when placed after a noun rather than before it, or when repeated, a classifier signifies a plural or indefinite quantity.
The terms "classifier" and "measure word" are frequently used interchangeably (as equivalent to the Chinese term 量词 (量詞) liàngcí, which literally means "measure word"). Sometimes, however, the two are distinguished, with classifier denoting a particle without any particular meaning of its own, as in the example above, and measure word denoting a word for a particular quantity or measurement of something, such as "drop", "cupful", or "liter". The latter type also includes certain words denoting lengths of time, units of currency, etc. These two types are alternatively called count-classifier and mass-classifier, since the first type can only meaningfully be used with count nouns, while the second is used particularly with mass nouns. However, the grammatical behavior of words of the two types is largely identical.
Most nouns have one or more particular classifiers associated with them, often depending on the nature of the things they denote. For example, many nouns denoting flat objects such as tables, papers, beds, and benches use the classifier 张 (張) zhāng, whereas many long and thin objects use 条 (條) tiáo. The total number of classifiers in Chinese may be put at anywhere from a few dozen to several hundred, depending on how they are counted. The classifier 个 (個), pronounced gè or ge in Mandarin, apart from being the standard classifier for many nouns, also serves as a general classifier, which may often (but not always) be used in place of other classifiers; in informal and spoken language, native speakers tend to use this classifier far more than any other, even though they know which classifier is "correct" when asked. Mass-classifiers might be used with all sorts of nouns with which they make sense: for example, 盒 hé ("box") may be used to denote boxes of objects, such as lightbulbs or books, even though those nouns would be used with their own appropriate count-classifiers if being counted as individual objects. Researchers have differing views as to how classifier–noun pairings arise: some regard them as being based on innate semantic features of the noun (for example, all nouns denoting "long" objects take a certain classifier because of their inherent longness), while others see them as motivated more by analogy to prototypical pairings (for example, "dictionary" comes to take the same classifier as the more common word "book"). There is some variation in the pairings used, with speakers of different dialects often using different classifiers for the same item. Some linguists have proposed that the use of classifier phrases may be guided less by grammar and more by stylistic or pragmatic concerns on the part of a speaker who may be trying to foreground new or important information.