A note on the three Scandinavian national letters:

The Danish and Norwegian three national letters æ, ø and å are vowels.
In Swedish text are used ä for æ and ö for ø.
The Swedish three national letters å, ä and ö are vowels too.

æ

is similar to German ä and sounds like a in ache.

capital æ = Æ
capital ä = Ä

ø

is similar to German ö and sounds like i in bird.

capital ø = Ø
capital ö = Ö

å

sounds like au in caught.

capital å = Å

Collating sequence (sorting order) in Denmark and Norway is:

a-z, æ, ø, å

Collating sequence (sorting order) in Sweden is slight different:

a-z, å, ä, ö

æ

is called a-e-ligature - in the ISO 8859-1 character set.

ä

is called a-umlaut - in the ISO 8859-1 character set.

ø

is called o-slash - in the ISO 8859-1 character set.

ö

is called o-umlaut - in the ISO 8859-1 character set.

å

is called a-ring - in the ISO 8859-1 character set.

The letters w, x and z are rarely seen in Scandinavian text today.