In linguistic typology, a null-subject language is a language whose grammar permits an independent clause to lack an explicit subject; such a clause is then said to have a null subject.
 In the principles and parameters framework, the null subject is controlled by the pro-drop parameter, which is either on or off for a particular language.[citation needed]
 Typically, null-subject languages express person, number, and/or gender agreement with the referent on the verb, rendering a subject noun phrase redundant.
 For example, in Italian the subject "she" can be either explicit or implicit:
 Borja Borja non not vuole want pagare. [to-]pay Borja non vuole pagare. Borja not want [to-]pay "Borja does not want to pay."   Subject Non not vuole want pagare. [to-]pay {} Non vuole pagare. Subject not want [to-]pay "[(S)he] does not want to pay." The subject "(s)he" of the second sentence is only implied in Italian. English and French, on the other hand, require an explicit subject in this sentence.
 Of the thousands of languages in the world, a considerable number are null-subject languages, from a wide diversity of unrelated language families. They include Albanian, Arabic, Basque, Berber, Bengali, Catalan/Valencian, Chinese, Estonian, Finnish, Galician, Gujarati, Greek, Hebrew, Hindi, Hungarian, Italian,  Romanian, Japanese, Korean, Maltese, Nepali,  Persian, Portuguese, Punjabi,  Sindhi, Slavic languages, Spanish, Tamil and the Turkic languages, as well as most languages related to these, and many others still.
 Languages which are not null-subject languages usually require an explicit subject. English and French make an exception for the imperative mood, or where a subject is mentioned in the same sentence, one immediately preceding it, or where the subject is implied. These languages can sometimes drop pronouns in limited contexts: e.g, German for "please", Bitte, literally means "[I] beg", and in English "Am not happy" or even "Not happy!" would be clearly understood as the first person singular "I am not happy". Similarly, in some cases the additional inclusion of pronouns in English has equivalent force to their optional inclusion in Spanish or Italian: e.g, "I cook, I wash up and I do the shopping" is more emphatic than simply "I cook, wash up and do the shopping".
 Subjects may sometimes be dropped in colloquial speech where the subject is implied.
 In the framework of government and binding theory of syntax, the term null subject refers to an empty category. The empty category in question is thought to behave like an ordinary pronoun with respect to anaphoric reference and other grammatical behavior. Hence it is most commonly referred to as "pro".
 This phenomenon is similar, but not identical, to that of pro-drop languages, which may omit pronouns, including subject pronouns, but also object pronouns. While all pro-drop languages are null-subject languages, not all null-subject languages are pro-drop.
 In null-subject languages that have verb inflection in which the verb inflects for person, the grammatical person of the subject is reflected by the inflection of the verb and likewise for number and gender.
 The following examples come from Portuguese:
 As the examples illustrate, in many null-subject languages, personal pronouns exist and can be used for emphasis but are dropped whenever they can be inferred from the context. Some sentences do not allow a subject in any form while, in other cases an explicit subject without particular emphasis, would sound awkward or unnatural.
 Most Bantu languages are null-subject. For example, in Ganda, 'I'm going home' could be translated as Ŋŋenze ewange or as Nze ŋŋenze ewange, where nze means 'I'.
 Arabic is considered a null-subject language, as demonstrated by the following example:
 sā‘id help ghayrak, other, yusā‘iduk helps you. sā‘id ghayrak, yusā‘iduk help other, {helps you}. "You help another, he helps you." Subject information for 'you' and 'he' is encoded in the conjugations of the verbs ساعِد and يساعد.
 Gəldim, came, gördüm, saw, işğal etdim conquered Gəldim, gördüm, {işğal etdim} came, saw, conquered I came, I saw, I conquered. ("Veni, vidi, vici") Дойдох, came, видях, saw, победих conquered Дойдох, видях, победих came, saw, conquered I came, I saw, I conquered. ("Veni, vidi, vici") In Catalan/Valencian, as in Spanish, Portuguese, Galician, etc., the subject is also encoded in the verb conjugation. Pronoun use is not obligatory.
 In Catalan/Valencian, one may choose whether to use the subject or not. If used in an inclined tone, it may be seen as an added emphasis; however, in colloquial speaking, usage of a pronoun is optional. Even so, sentences with a null subject are used more frequently than sentences with a subject. In some cases, it is even necessary to skip the subject to create a grammatically correct sentence.
 Most varieties of Chinese tend to be non-null-subject. Verbs in Chinese languages are not conjugated, so it is not possible to determine the subject based on the verb alone. However, in certain circumstances, most Chinese varieties allow dropping of the subject, thus forming null-subject sentences. One of the instances where the subject would be removed is when the subject is known. Below is an example in Mandarin:
 妈妈: māma: mother: 不 bú Not 要 yào want 忘 wàng forget 了 le PERF 丢 diū throw 垃圾。 lāji rubbish. 妈妈: 不 要 忘 了 丢 垃圾。 māma: bú yào wàng le diū lāji mother: Not want forget PERF throw rubbish. Mother: "Do not (you) forget to take out the rubbish." 妹妹: mèimèi: younger sister: 知道 zhīdào (I)know 啦。 la PTCL 妹妹: 知道 啦。 mèimèi: zhīdào la {younger sister:} (I)know PTCL Younger sister: "(I) know it." The above example clearly shows that a speaker could omit the subject if the doer of the verb is known. In a Chinese imperative sentence, like the first text, the subject is also left out.
 In Galician, as in Spanish, Portuguese, Catalan, etc., the subject is also encoded in the verb conjugation. Pronoun use is not obligatory.
 In Galician, one may choose whether to use the subject or not. If used in an inclined tone, it may be seen as an added emphasis; however, in colloquial speaking, usage of a pronoun is optional. Even so, sentences with a null subject are used more frequently than sentences with a subject. In some cases, it is even necessary to skip the subject to create a grammatically correct sentence.
 Ήρθα, Írtha, came, είδα, eída, saw, νίκησα. níkisa. conquered. Ήρθα, είδα, νίκησα. Írtha, eída, níkisa. came, saw, conquered. I came, I saw, I conquered. (equivalent of "Veni, vidi, vici" in Latin) Hebrew is considered a partially null-subject language, as demonstrated by the following example:
 azor help l'acherim, others, ya'azru will-help l'kha you azor l'acherim, ya'azru l'kha help others, will-help you You help others, they will help you. Subjects can usually be omitted only when the verb is conjugated for grammatical person, as in the third-person plural in the example above.
In Hebrew one can also construct null-subject sentences as in the Latin and Turkish language examples: "We/you/they are going to the beach" can be expressed as "holkhim la-yam" (הולכים לים), lit. "Are going to the beach." This is truly a null-subject construction.
 As in Spanish and Turkish, though, Hebrew conjugates verbs in accordance with specific pronouns, so "we went to the beach" is technically just as much a null-subject construction as in the other languages, but in fact the conjugation does indicate the subject pronoun: "Halakhnu la-yam" (הלכנו לים), lit. "Went (we) to the beach." The word "halakhnu" means "we went", just as the Spanish and Turkish examples indicate the relevant pronoun as the subject in their conjugation. So these should perhaps not be considered to be true null-subject phrases. Potentially confusing the issue further is the fact that Hebrew word order can also make some sentences appear to be null-subject, when the subject is in fact given after the verb. For instance, "it's raining" is expressed "yored geshem" (יורד גשם), which means "descends rain"; "rain" is the subject. The phrases meaning "It's snowing" and "It's hailing" are formed in the same way.[citation needed]
 Hindi shows radical pro-drop. This type of pro-drop differs from pro-drop in languages like Spanish where pro-drop is licensed by rich verbal morphology. Radical pro-drop is possible only in NP languages. South Asian languages such as Hindi, in general, have the ability to pro-drop any and all arguments. Here, the case is expressed in a morpheme that is independent from the stem, making the pro-drop possible. 
 bārish rain:DIR ho happen:VRB rahī stay:FEM:SG hai. is:3P:SG bārish ho rahī hai. rain:DIR happen:VRB stay:FEM:SG is:3P:SG 'It is raining.' tum-ne you:ERG nādyā-ko nadya:DAT khānā food:DIR di-yā give:PRF:MASC:SG tum-ne nādyā-ko khānā di-yā you:ERG nadya:DAT food:DIR give:PRF:MASC:SG 'Did you give food to Nadya?' hā̃ yes diyā give:PRF:GND:MASC:SG hā̃ diyā yes give:PRF:GND:MASC:SG 'Yes, (I) gave (food to her).' Faccio una torta. Faccio una torta. (I)bake a cake. Chiama i suoi genitori. Chiama i suoi genitori. (He/She)calls his/her parents. The conjugations of the root verbs (faccio for fare; chiama for chiamare) already imply the subject of the sentences.
 Japanese and several other null-subject languages are topic-prominent languages; some of these languages require an expressed topic in order for sentences to make sense. In Japanese, for example, it is possible to start a sentence with a topic marked by the particle wa, and in subsequent sentences leave the topic unstated, as it is understood to remain the same, until another one is either explicitly or implicitly introduced. For example, in the second sentence below, the subject ("we") is not expressed again but left implicit:
 私達 Watashitachi We は wa TOP 買い物 kaimono shopping を o OBJ した。 shita. did. 後 Ato After で de COMPL ご飯 gohan dinner を o OBJ 食べた。 tabeta. ate. 私達 は 買い物 を した。 後 で ご飯 を 食べた。 Watashitachi wa kaimono o shita. Ato de gohan o tabeta. We TOP shopping OBJ did. After COMPL dinner OBJ ate. "We went shopping. Afterwards, we ate dinner." In other cases, the topic can be changed without being explicitly stated, as in the following example, where the topic changes implicitly from "today" to "I".
 今日 Kyō Today は wa TOP ゲーム gēmu game の no GEN 発売日 hatsubaibi release date なんだ na n da is けど、 kedo, but, 買おうか kaō ka whether to buy どうか dō ka or not 迷っている。 mayotte iru. confused. 今日 は ゲーム の 発売日 なんだ けど、 買おうか どうか 迷っている。 Kyō wa gēmu no hatsubaibi {na n da} kedo, {kaō ka} {dō ka} {mayotte iru}. Today TOP game GEN {release date} is but, {whether to buy} {or not} confused. "The game comes out today, but (I) can't decide whether or not to buy (it)." It is also common for Japanese to omit things which are obvious in context. If the above line were part of a conversation about considering purchasing the game, it could be further shortened to:
 発売日 Hatsubaibi Release day だけど、 dakedo, but 迷っている。 mayotte iru. not sure. 発売日 だけど、 迷っている。 Hatsubaibi dakedo, {mayotte iru}. {Release day} but {not sure}. "(It's the game's) release day, but (I) can't decide (whether or not to buy it)." Verb-conjugation endings in Latin express number and person (as well as tense and mood).
 Veni, Came-I, vidi, saw-I, vici conquered-I Veni, vidi, vici Came-I, saw-I, conquered-I I came, I saw, I conquered. Cogito Think-I, ergo therefore sum. am Cogito ergo sum. Think-I, therefore am I think, therefore I am. Дојдов, came, видов, saw, победив. conquered Дојдов, видов, победив. came, saw, conquered I came, I saw, I conquered. ("Veni, vidi, vici") Myślę, (I) think, więc therefore jestem. (I) am. Myślę, więc jestem. {(I) think}, therefore {(I) am}. I think, therefore I am. ("Cogito ergo sum") In Polish, the subject is omitted almost every time, although it can be present to put emphasis on the subject.
 Пришёл, came, увидел, saw, победил conquered. Пришёл, увидел, победил came, saw, conquered. I came, I saw, I conquered. ("Veni, vidi, vici") āyus, dditham, khatiyus āyus, dditham, khatiyus I came, I saw, I conquered. ("Veni, vidi, vici") With subjects: آئون آيس، مون ڏٺو، آئون، کٽيس
Idiomatic translation: I came, I saw, I conquered.
 In Spanish, as with Latin and most Romance languages, the subject is encoded in the verb conjugation. Pronoun use is not obligatory.
 In Spanish, for the most part one may choose whether to use the subject or not. Generally if a subject is provided, it is either for clarity or for emphasis. Sentences with a null subject are used more frequently than sentences with a subject.
 Verb conjugations in Tamil incorporate suffixes for number (singular and plural) and person (1st, 2nd and 3rd), and also for gender (masculine, feminine and neuter) in the third person. An explicit subject, therefore, is unnecessary, and can be inferred from the verb conjugation.
 Tamil script: முடிந்துவிட்டது Transliteration: muḍinduviṭṭaduLiteral Translation: It has left, having ended.Idiomatic Translation: It has come to an end.
 Another example:
 பந்தை Pantai Ball(ACC) அவரிடம் avariṭam him(LOC) கொடுத்தேன் koṭuttēṉ gave பந்தை அவரிடம் கொடுத்தேன் Pantai avariṭam koṭuttēṉ Ball(ACC) him(LOC) gave (I) gave him the ball Geldim, (I) came, gördüm, (I) saw, yendim. (I) conquered Geldim, gördüm, yendim. {(I) came}, {(I) saw}, {(I) conquered} I came, I saw, I conquered. ("Veni, vidi, vici") Düşünüyorum, (I) Think, öyleyse therefore varım. (I) exist. Düşünüyorum, öyleyse varım. {(I) Think}, therefore {(I) exist}. I think, therefore I am. ("Cogito ergo sum") In some cases (impersonal constructions), a proposition has no referent at all. Pro-drop languages deal naturally with these, whereas many non-pro-drop languages such as English and French must fill in the syntactic gap by inserting a dummy pronoun. "*Rains" is not a correct sentence; a dummy "it" must be added: "It rains"; in French "Il pleut". In most Romance languages, however, "Rains" can be a sentence: Spanish "Llueve", Italian "Piove", Catalan "Plou", Portuguese "Chove", Romanian "Plouă", etc. Uralic and Slavic languages also show this trait: Finnish "Sataa", Hungarian "Esik"; Polish "Pada".
 There are constructed languages that are not pro-drop but do not require this syntactic gap to be filled. For example, in Esperanto, "He made the cake" would translate as Li faris la kukon (never *Faris la kukon), but It rained yesterday would be Pluvis hieraŭ (not *Ĝi pluvis hieraŭ).
 Other languages (sometimes called non-null-subject languages) require each sentence to include a subject: this is the case for most Germanic languages, including English and German, as well as many other languages. French, though a Romance language, also requires a subject. In some cases—particularly in English, less so in German, and occasionally in French—colloquial expressions allow for the omission of the subject in a manner similar to that of Spanish or Russian:[vague][citation needed]
 Even in such non-null-subject languages such as English, it is standard for clauses in the imperative mood to lack explicit subjects; for example:
 An explicit declaration of the pronoun in the imperative mood is typically reserved for emphasis:
 French and German offer less flexibility with respect to null subjects. 
 In French, it is neither grammatically correct nor possible to include the subject within the imperative form; the vous in the expression taisez-vous stems from the fact that se taire, "to be silent," is a reflexive verb and is thus the object with similar meaning to "yourself" in an English imperative.[citation needed]
 In German, the pronoun (singular du or plural ihr) is normally omitted from the informal second-person imperative (Mach das, "Do it"), although it may be added in a colloquial manner for emphasis (Macht ihr das!, "You [guys] do it!"). By contrast, the addressee-specific formal imperative requires the addition of the pronoun Sie (as in Machen Sie das!, "Do it, [sir/ma'am]!") to avoid confusion with the otherwise morphologically identical infinitive, whereas the addressee-nonspecific or "neutral" formal imperative omits the pronoun and moves the verb to final position (as in Bitte nicht stören, "Please do not disturb"). On the other hand, the pronoun wir is always included in the first-person plural imperative (Machen wir das!, "Let's do it!"), with the verb appearing in first position to differentiate the imperative from the indicative mood, wherein the verb appears in second position (as in Wir machen das, "We're doing it").
 Many international auxiliary languages, while not officially pro-drop, permit pronoun omission with some regularity.
 In Interlingua, pronoun omission is most common with the pronoun il, which means "it" when referring to part of a sentence or to nothing in particular. Examples of this word include
 Il tends to be omitted whenever the contraction "it's" can be used in English. Thus, il may be omitted from the second sentence above: "Es ver que ille arriva deman". In addition, subject pronouns are sometimes omitted when they can be inferred from a previous sentence:
 Similarly, Esperanto sometimes exhibits pronoun deletion in casual use. This deletion is normally limited to subject pronouns, especially where the pronoun has been used just previously:
 Ĉu QUESTION-PARTICLE vi you vidas see lin? him? Venas Comes nun. now. Ĉu vi vidas lin? Venas nun. QUESTION-PARTICLE you see him? Comes now. Do you see him? He is coming now. In "official" use, however, Esperanto admits of null-subject sentences in two cases only:
 Contrary to the Interlingua example above, and as in English, a repeated subject can normally be omitted only within a single sentence: