The letter "ق" (Qaf) is the 21st letter of the Arabic alphabet. It is pronounced as a voiceless uvular plosive, similar to the "k" sound but produced further back in the throat. In Arabic script, "ق" has different forms depending on its position in a word: initial, medial, final, or isolated. In terms of numerical value, "ق" represents the number 100 in the Arabic numeral system. It is commonly used in various Arabic words, including قلب (heart) and قمر (moon). The letter is also significant in Islamic texts and literature, where it appears frequently.