A letter -- most often a vowel -- that has two dots placed over it can be a diaeresis, trema or umlaut. These diacritics are used in many languages, including English, French and Spanish. The iPhone is capable of using diacritics, including diaereses. Furthermore, you don't need to change the phone or keyboard language to insert such a character into your text messages, notes or emails.

Inserting Diaereses on iPhone

Launch the app you want to use to create or edit the text message, note or email. Tap and hold on the letter "E" on the iPhone's on-screen keyboard until an additional menu is displayed. Tap the diaeresis you wish to use to insert it into the text. The menu disappears when you tap the letter.