Umlauts are a common occurrence in the German language and generally represented as two dots above a letter. Most of the umlaut letters are located in the "Special Characters" tool, but learning a few simple keystrokes makes creating umlauts much easier and will keep you from having to constantly open the tool. The shortcut for creating an umlaut also is simpler on a Mac than PC.
Press and hold the "Alt" key on your keyboard while you press the letter "u." Release the "Alt" key. A highlighted symbol will appear to the left of the cursor.
Press the letter over which you would like to create the umlaut. Supported letters are "a," "o" and "u." The letter will be replaced with an umlaut version of the letter.
Press the shift key along with the letters "a," "o" and "u" to make a capitalised version of the letters. Remember to press "Alt+u" first, however.
You can view umlaut characters and many other symbols in most word processors and text editors on a Mac by clicking "Edit" in the top toolbar and clicking "Special Characters" or by pressing "Cmd" plug "Alt" plus "T" on your Mac's keyboard.