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. 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: 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. In fact, it is rather the absence of pronoun dropping that is an areal feature of Standard Average European, including French, German, and English. Characterization 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