Characteristic features of Finnish (common to other Finno-Ugric languages) are vowel harmony and an agglutinative morphology; due to the extensive use of the latter, words can be quite long. The main stress is always on the first syllable.
There are eight vowels, whose lexical and grammatical role is highly important, and which are unusually strictly controlled, so that there is almost no allophony. Vowels are as follows, followed by IPA when not identical: a [?], e, i, o, u, y, ä [æ], ö [ø]. The vowels a, o, u have front counterparts ä, ö, y in the vowel harmony, where i and e are neutral. One phoneme is the chroneme, such that Finnish appears to have long and short vowels and consonants; thus, long vowels behave as vowels followed by a consonant, not as lengthened vowels. The quality of long vowels mostly overlaps with the quality of short vowels, with the exception of u, which is centralized with respect to uu. There are eighteen phonemic diphthongs; just as vowels, diphthongs do not have allophony.
Finnish has a consonant inventory of small to moderate size, where voicing is not distinctive, and there are only glottal and unvoiced alveolar fricatives. Almost all consonants are either alveolar or pronounced such that the tongue doesn't have to move away from the alveolar ridge.
1. /d/ is the equivalent of /t/ under weakening consonant gradation,
and thus occurs only medially, or in non-native words; it is actually
more of a alveolar tap rather than a true voiced stop, and the dialectal
realization varies wildly; see main article.
2. The glottal stop is not a phoneme, but is found as a result of lenition of /k/ between a long vocalic sound and a short vowel in words such as ruo'on ? ruoko. It can also be analyzed as a hiatus.
Almost all consonant have phonemic geminated forms. These are independent, but occur only medially when phonemic.
Independent consonant clusters are not allowed in native words, except for a small set of two-consonant syllable coda, e.g. 'rs' in torstai. However, due to a number of loanwords using them, e.g. strutsi "ostrich", Finnish speakers can pronounce them, even if it is somewhat awkward.
As a Finno-Ugric language, it is somewhat special in three respects: noninitial labial vowels, loss of fricatives and palatalization.
An interesting feature of Fennic phonology is the development of labial vowels in non-initial syllables. Proto-Uralic had only 'a' and 'i' and their vowel harmonic allophones in non-initial syllables, but modern Finnish allows other vowels in non-initial syllables, albeit they are uncommon compared to 'a', 'ä' and 'i'.
Palatalization is characteristic to Finno-Ugric languages, but standard Finnish has lost it. The palatalization is replaced by /j/; the sound /j/ has become independent, in spelling as in pronunciation ; it becomes /i/ in a word-final position. The Eastern dialects and the Karelian language retain palatalization.