A topic-prominent language is one that organizes its syntax so that sentences have a topic-comment (or theme-rheme) structure, where the topic is the thing being talked about (predicated) and the comment is what is said about the topic. This structure is independent of the syntactic ordering of subject, verb and object, and may be marked by word order (typically mentioning the topic first thing in the sentence, and then the comment), or by explicit morphology (as in Japanese with the clitic particle wa).

The difference between topic-prominent languages and non-topic-prominent languages is that topic marking is done systematically in the former, while the latter resort to various idiosyncratic means for topicalization (see "Topic" for English examples).

Examples of topic-prominent languages are the Chinese languages, Japanese and Korean.

Common features of topic-prominent languages

• They tend to downplay the role of the passive voice, if a passive construction exists at all, since the main idea of passivization is to turn an object into a subject in languages where the subject is understood to be the topic by default. The Japanese passive voice has a specific connotation that restricts its use.
• They usually don't have "dummy subjects" like English "it" in "It's raining". Since topic-prominent languages don't consider the subject, but the topic, to be the most important part of the sentence, it may not matter if there's no apparent subject.
• They often have sentences with so-called "double subjects", actually a topic plus a subject, for example: Sono yashi wa happa ga ookii desu (Japanese) — "That palm tree (topic), leaves (subject) are big".