The letter "ع" is the Arabic letter known as "Ayn." It is the 18th letter in the Arabic alphabet and represents a voiced pharyngeal fricative sound. This sound does not have a direct equivalent in English, making it unique and challenging for non-native speakers to pronounce. In Arabic script, "ع" can appear in different forms depending on its position in a word: initial, medial, or final. It is often used in various Arabic words, including names and common phrases, contributing to the rich phonetic diversity of the language.