Dental, alveolar and postalveolar nasals
The alveolar nasal is a type of consonantal sound used in numerous spoken languages. The symbol in the International Phonetic Alphabet that represents dental, alveolar, and postalveolar nasals is ⟨n⟩, and the equivalent X-SAMPA symbol is
The vast majority of languages have either an alveolar or dental nasal. There are a few languages that lack either sound but have [m] (e.g. colloquial Samoan). There are some languages (e.g. Rotokas) that lack both [m] and [n].
True dental consonants are relatively uncommon. In the Romance, Dravidian, and Australian languages, n is often called "dental" in the literature. However, the rearmost contact (which is what gives a consonant its distinctive sound) is actually alveolar or denti-alveolar. The difference between the Romance languages and English is not so much where the tongue contacts the roof of the mouth, as which part of the tongue makes the contact. In English it is the tip of the tongue (such sounds are termed apical), whereas in the Romance languages it is the flat of the tongue just above the tip (such sounds are called laminal).
However, there are languages with true apical (or less commonly laminal) dental n. It is found in the Mapuche language of South America, where it is actually interdental. A true dental generally occurs allophonically before /θ/ in languages which have it, as in English tenth. Similarly, a denti-alveolar allophone will occur in languages which have denti-alveolar stops, as in Spanish cinta.
Some languages contrast laminal denti-alveolar and apical alveolar nasals. For example, in the Malayalam pronunciation of Nārāyanan, the first n is dental, the second is retroflex, and the third alveolar.