I am just back from a presentation on musicology and once more I realised that the German Umlaute can be more than confusing and also inviting you to drop them if you do not have a German keyboard installed. What the heck, they will understand me anyway, right? Answer: depends. In the worst case you will find youself in an embarassing situation. Here are some examples:
In musicology we talked about Schlager. That is a kind of song that is very basic in language, simple in music and you hear it played often in certain type of bars. There is not such a word in English. Lucky you, the lack of vocabulary might have also spared you this kind of music. In Spain it would be Julio Iglesias. Okay, that is a Schlager (song). What is Schläger? It can be a racket (e.g. for tennis) or simply a rowdy.
schwül, meaning hot and humid - best description for summer weather
schwul, means gay
If you find more words, please post a comment.
Here is how to get around it when the keyboard is not international. You can replace the Umlaut by adding the letter "e":
ä = ae
ö = oe
ü = ue
Be careful with names. Some people spell their name without Umlaut and it would be incorrect to just change their name to Umlaute.