It's called a diaeresis. It marks the start of a new syllable. They have an article discussing its history at the magazine. http://www.newyorker.com/online/blo

It's called a diaeresis. It marks the start of a new syllable. They have an article discussing its history at the magazine. http://www.newyorker.com/online/blogs/culture/2012/04/the-curse-of-the-diaeresis.html http://www.newyorker.com/online/blogs/culture/2012/04/the-cu...