Special German letters
1)
The grapheme ß, called Eszett ("sharp S")
The grapheme ß, called Eszett ("sharp S"), represents the [
s] phoneme in Standard German, specifically when following long vowels and diphthongs, while ss is used after short vowels. The name Eszett combines the names of the letters of s (Es) and z (Zett) in German. The character's Unicode names in English are sharp s and eszett.
My mother's last name Theiß (
how to pronounce) is spelled with such a "sharp s" - but sometimes you also see the substitute "ss" as it sounds similar - the international spelling of Theiß is
Theiss as the special character does not exist. It sounds equal!
BUT in my humble opinion, dropping one "s" =
Theis, is somehow not correct, not sure if there's a name Theis in Germany as well.
Some "Theiß families" in Wahnwegen, where my grandfather was born have all the same spelling! See the screenshot of a phonebook below!

For further details about the ß check this link
here
2)
Umlaute
There's another special letter which causes a confusion sometimes but I promise it's pretty easy if you pay attention to the rules.
Germanic Umlaute are:
Ä, ä, Ö, ö and
Ü, ü -> that's all!
Example: my name Jürgen Feldmann (German spelling with Umlaut) becomes Juergen Feldmann (like on my credit card)!
valid substitute: (please note the first character of a noun in German is capitalized!)
| Ä = Ae |
ä = ae |
Ö = Oe |
ö = oe |
Ü = Ue |
ü = ue |
So simply dropping the two dots does not make sense in German!
Example:
Krähenhöhle = Kr
aehenh
oehle (correct!), Krahenhohle (this spelling does not make sense!)
For further details about the Umlaute check this link
here
Here's a little entertaining video about German vs. English, just to relax and smile a bit