Grammar is a set of linguistic and structural rules describing how words work together to communicate meaning. Grammar can be classified into two groups: morphology and syntax. Morphology includes the study of word structure, as well as changes to words and their classification. Syntax refers to the study of how phrases and sentences are formed, the elements of a sentence, and the types of sentences. The most prominent feature of grammar is its abstraction and generality. The links between specific words and sentences are unlimited; but the ways in which they can be linked are not. Grammar is precisely such a set of well-defined, complex rules for linking. Different languages have different grammars, each with its own distinctive traits.  

The sentence is a basic unit of language and it is composed of words, phrases, and clauses. It has a relatively complete meaning, capable of fulfilling simple communication. Each sentence carries a certain tone and intonation by which it conveys additional information. In normal and continuous speech, sentences are usually separated by clear pauses.

Based on structure, phrases can be classified as coordinative phrases, endocentric phrases, post-complementary phrases, verb-object phrases, subject-predicate phrases, appositive phrases, serial-verb phrases, and verb-object plus subject-predicate phrases.

A coordinative phrase refers to a phrase with two or more elements linked together, each with equal weight. An endocentric phrase has two parts: the secondary that goes first and the primary that follows. The former modifies or restricts the latter; the former is called the modifier, and the latter is the substantive. A post-complementary phrase consists of two parts—the predicate, which describes an action or its status and the complement, which offers a supplementary description of the former. A verb-object phrase includes two parts—the predicate which describes an action or a behavior and the object—a person or a thing—towards which a specified action is directed. A subject-predicate phrase is made up of two parts, the subject that is being described or dealt with, and the predicate which states or describes the subject. An appositive phrase is one that renames the noun or noun phrase immediately before it. A serial-verb phrase is also called catenative or linked verb phrase. It has two or more verbs or verb phrases used consecutively without any other words coordinating or modifying them. Furthermore, the sentence does not have any connective or apparent pauses either. A verb-object plus subject-predicate phrase refers to a verb-object phrase combined with a subject-predicate phrase. The object of the verb-object phrase acts as the subject of the subject-predicate phrase.

Based on function, however, phrases can be divided into noun and non-noun phrases. The grammatical function of a noun phrase is the same as for any other nouns. A non-noun phrase is also called a predicate phrase; its grammatical function is equivalent to a verb or an adjective.   

The word is the smallest unit capable of making a sentence; with certain pronunciations, semantic and grammatical functions it can be used independently. Parts of speech, or word classes, are determined by the grammatical classification of words. The meaning and the form of a word is reference-based. A word’s grammatical function refers to its ability to combine with other words, and to its position and function within a sentence. Whether the word can be used alone as an independent part of a sentence depends on whether the word can fit into one of two categories: notional words or functional words.

Notional words are words that can act as an independent part of a sentence. They have real meaning, and are free (meaning that they are not bound to certain other words or structures). They are used less frequently, some would say moderately, and most of them have a fixed tone. Notional words include nouns, verbs, adjectives, auxiliary verbs, numerals, classifiers (measure words), adverbs, and pronouns. Among them, the meanings of adverbs and pronouns are not as solid as the meanings of other word classes.

A function word cannot be used independently in a sentence; it is closely related to the grammatical structure of the sentence. Function words do not represent real meaning; they express grammatical relationships and belong to the enumerable categories, namely, the bound categories. These words are used frequently, and most of them do not have a fixed tone—they are pronounced with a light or unstressed tone. The grammatical function of these words may include use as a suffix or a conjunction. Function words include prepositions, conjunctions, and auxiliary words.

In Chinese grammar, sentences quite often include the word “ba” (used when the object is the recipient of the action from the ensuing verb), and “bei” (used in a passive sentence to introduce the agent or doer). Condensed sentences and elliptical sentences are also commonly used. To use Chinese correctly and fluently, it is quite helpful to master these commonly used sentence patterns. When speaking or writing Chinese, one will sometimes encounter grammatical errors such as an improper, incomplete, or redundant word; other times one may encounter incorrect word order, and mixed or unclear references or functional words. However, if one can grasp the main structure of a sentence, one can overcome these issues by adjusting the word order appropriately.