Umlauts are those vowels with two dots over them (ä, ö, ü) They change the pronunciation of a word and may even indicate a plural of the noun or a different definition.

We can get them on our machines, if you: have "Num Lock" on, then press the Alt key plus the following numbers to get the desired umlaut (and the double "ss" - ß)

ä = alt + 132 (on the number pad)
ö = alt + 148
ü = alt + 129
Ä = alt + 142
Ö = alt + 153
Ü = alt + 154
ß = alt + 125

Try it--its good to spell things correctly, especially when we're dealing with place names.