Sentence-final particle

Sentence-final particles, including modal particles, interactional particles, etc., are minimal lexemes (words) that occur at the end of a sentence and that do not carry referential meaning, but may relate to linguistic modality, register or other pragmatic effects. Sentence-final particles are common in Chinese, including particles such as Mandarin "le" 了, "ne" 呢, "ba" 吧, "ou" 哦, "a" 啊, "la" 啦, "ya" 呀, and "ma" 嗎/吗, and Cantonese "lo" 囉 and "ge" 嘅. These particles act as qualifiers of the clause or sentence they end. Sentence-final particles are also present in Japanese and many East Asian languages, such as Thai, and especially in languages that have undergone heavy Sino-Tibetan influence, such as the Monguor languages.
Examples.
Chinese.
Yuen Ren Chao has described sentence-final particles as "phrase suffixes": just as a word suffix is in construction with the word preceding it, a sentence-final particle or phrase suffix is "in construction with a preceding phrase or sentence, though phonetically closely attached to the syllable immediately preceding it". According to Chao, the sentence-final particle is phonetically close to the last word before it, but syntactically it is equidistant from every word in the whole predicate.
While sentence-final particles usually do not carry meaning themselves or denote anything explicit, they may be derived from words that do carry meaning when they occur in other contexts and serve different functions.
All of the sentence-final particles of Standard Chinese are unstressed and, unlike most syllables in the language, do not carry tone.
A major use of sentence-final particles in Mandarin Chinese specifically is thought to be as a signal of the speaker's attitude, the intended force of the statement to which the particle is attached, and "how the utterance is to be taken by the hearer." For example, the addition of a particle may soften the tone of a question that might sound presumptuous or inappropriate without the particle. As such, sentence-final particles in this sense often perform an interpersonal function, rather than a grammatical one. Nevertheless, there are cases in which sentence-final particles do perform grammatical functions, such as Mandarin "ma" 嗎/吗, the "question particle," which changes the grammatical mood of a sentence to interrogative. Likewise, even though sentence-final particles can usually be omitted from a sentence without making the sentence ungrammatical or changing its meaning, some particles do contain information critical to the interpretation of an utterance's meaning, such as Mandarin "le" 了.
Japanese.
In Japanese, there are many sentence-final particles that are used in formal as well as colloquial speech. Some examples include:
English.
English also has some words and phrases that act somewhat like sentence final particles, but primarily only in colloquial speech. However, there are others, called tag questions, which are less colloquial and can be used for any situation. All are generally discourse particles rather than modal particles. For example:
All but the first are tag questions. Notice how when the main sentence is affirmative, the tag question is negative, and vice versa.
Spanish.
In the same way that certain words and phrases are used as sentence final particles above in the section on English (as discourse particles), some Spanish words and phrases can be used this way as well; once again, these are usually called tag questions. For example:
Note that in Spanish, the question marks are placed around the tag question, and not around the entire sentence (although English only uses the single final question mark, it is implied that the entire sentence, and not just the tag, is the question).