Long and short sounds are a main factor in being able to speak, read and write Finnish, as different words can have different meanings depending on if the word has a long or short sound in it.
 

In Finnish, sounds can be divided into 2 distinct groups: vowels and consonants. Both groups can be written with double letters to indicate that they are long sounds, e.g. a vs. aa. Every sound in Finnish can be either short or long, except for d, h, j and v.