<P> Change also happens in the grammar of languages as discourse patterns such as idioms or particular constructions become grammaticalized . This frequently happens when words or morphemes erode and the grammatical system is unconsciously rearranged to compensate for the lost element . For example, in some varieties of Caribbean Spanish the final / s / has eroded away . Since Standard Spanish uses final / s / in the morpheme marking the second person subject "you" in verbs, the Caribbean varieties now have to express the second person using the pronoun tú . This means that the sentence "what's your name" is ¿ como te llamas? (ˈkomo te ˈjamas) in Standard Spanish, but (ˈkomo ˈtu te ˈjama) in Caribbean Spanish . The simple sound change has affected both morphology and syntax . Another common cause of grammatical change is the gradual petrification of idioms into new grammatical forms, for example, the way the English "going to" construction lost its aspect of movement and in some varieties of English has almost become a full - fledged future tense (e.g. I'm gonna). </P> <P> Language change may be motivated by "language internal" factors, such as changes in pronunciation motivated by certain sounds being difficult to distinguish aurally or to produce, or through patterns of change that cause some rare types of constructions to drift towards more common types . Other causes of language change are social, such as when certain pronunciations become emblematic of membership in certain groups, such as social classes, or with ideologies, and therefore are adopted by those who wish to identify with those groups or ideas . In this way, issues of identity and politics can have profound effects on language structure . </P> <P> One important source of language change is contact and resulting diffusion of linguistic traits between languages . Language contact occurs when speakers of two or more languages or varieties interact on a regular basis . Multilingualism is likely to have been the norm throughout human history and most people in the modern world are multilingual . Before the rise of the concept of the ethno - national state, monolingualism was characteristic mainly of populations inhabiting small islands . But with the ideology that made one people, one state, and one language the most desirable political arrangement, monolingualism started to spread throughout the world . Nonetheless, there are only 250 countries in the world corresponding to some 6000 languages, which means that most countries are multilingual and most languages therefore exist in close contact with other languages . </P> <P> When speakers of different languages interact closely, it is typical for their languages to influence each other . Through sustained language contact over long periods, linguistic traits diffuse between languages, and languages belonging to different families may converge to become more similar . In areas where many languages are in close contact, this may lead to the formation of language areas in which unrelated languages share a number of linguistic features . A number of such language areas have been documented, among them, the Balkan language area, the Mesoamerican language area, and the Ethiopian language area . Also, larger areas such as South Asia, Europe, and Southeast Asia have sometimes been considered language areas, because of widespread diffusion of specific areal features . </P>

The set of rules that governs the proper use and combination of language symbols is