When optimizing sites in languages that contain characters not found in the English language, it is important to know that Google will return different results depending on whether the characters (called diacritical marks or diacritics) were used. For example, a search for “Rucksäcke” (the German word for backpacks) on Google.de returns different results than one for “Rucksacke” (which is technically a typo) or “Rucksaecke”, the common form used in German speaking countries when the umlaut is not available.
Similarly, when using Google.fr, the results for a search for “café” are different from those for “café” (without the accent). Granted, the top ten results are similar but the ranking of them is not the same. It would appear that the factors most responsible for this anomaly are the inclusion (or not) of the diacritical marks in the title and URL.
What is the significance of this to global marketers? That really depends on the location of your customer and the type of keyword they are using.
German speaking customers in Germany use keyboards with umlauts so their search terms will always include them. To stand a better chance of reaching them, you’ll want to optimize your title tags with the keywords in diacritic form such as “Rucksäcke”. If you can also include the diacritic form of the keyword in the URL, then you stand a better chance of gaining higher ranking. This is tricky but can be achieved through a URL rewrite.
However, German businesses marketing to people in the United Kingdom and/or United States should realize that their target customers will not likely use diacritical marks. An example of where this could be important is with the use of the German word Straße meaning street in English. Vacationers in the UK or US would replace the use of the eszett (ß) with a double s. Therefore, tourism-related businesses targeting people where the use of diacritical marks in not the norm should optimize for word forms that replace these marks, for example strasse instead of Straße.