A language border or language boundary is the line separating two language areas. The term is generally meant to imply a lack of mutual intelligibility between the two languages. If two adjacent languages or dialects are mutually intelligible, no firm border will develop, because the two languages can continually exchange linguistic inventions; this is known as a dialect continuum. A "language island" is a language area that is completely surrounded by a language border. Important concepts The concept of mutual intelligibility is vague. More important, it can be difficult for non-native speakers to distinguish one language from one another similar one. Furthermore, there is no clear definition of what constitutes a language: for instance some languages share writing systems but are spoken differently, while others are identical when spoken but are written using different alphabets. For example, different "dialects" of Chinese use the same characters with the same meanings, but these can be pronounced very differently in different varieties. Japanese also uses large numbers of Kanji characters (of Chinese origin) to mean the same as in Chinese, but they often have different "readings" (yomi) some of which may be pronounced as in Chinese while others are totally different. There are often also shared terms between two languages even between languages that have nothing to do with each other. For example, Spanish is spoken in most Central American and South American countries, but also in Spain. There are subtle but recognizable differences between the dialects, but there are different dialects even within the country of Spain. (In many cultures there also slight differences between the versions of the language, both spoken and written ("registers") used in different contexts: for example when talking to one's boss and talking to one's friends.) Difficulties There can also be people within a country who speak the "native" language of a different country, some of whom may be bilingual. Also, an inherited language may evolve and perhaps absorb some of the characteristics or terms of the new area's predominant language. In cases such as these, it becomes even more difficult to identify specific languages. When speakers have a foreign accent, they are often perceived to be less intelligent and are less likely to be hired. It is the same with an accent from a peripheral area, rather than the accent from the urbanized core: a peripheral person is typically perceived as speaking a "less correct" by