Whÿ ärë thërë ëÿëš öñ thëšë łëttërš¿?

Most often called an umlaut (German), sometimes called a diaresis, the two dots indicate either a change in that vowel’s sound (“umlaut” means “about sound”) or the pronunciation of an ordinarily silent letter, such as in “naïve”. Only a few languages (such as Albanian & Tagalog) use two dots over an e. Wikipedia has a great entry on the subject: wikipedia.org/wiki/Diaeresis_(diacritic). I see that your s’s have smiles over them.