مد (Extension) refers to the elongation of a sound in the Arabic language, particularly in the context of Tajweed, which is the art of reciting the Quran. It involves prolonging certain vowels to enhance the beauty and clarity of the recitation. This practice is essential for proper pronunciation and understanding of the text. In Arabic, there are specific rules governing the length of the extension, which can vary based on the letters and surrounding sounds. The most common types of extensions include Madd (natural extension), Madd Lazim (obligatory extension), and Madd Munfasil (separated extension). Each type has its own guidelines for duration and application.