The letter "t" is the 20th letter of the English alphabet. It is a consonant and is often used in various words to create sounds. In phonetics, "t" is classified as a voiceless alveolar plosive, meaning it is produced by obstructing airflow in the vocal tract. In mathematics, "t" can represent a variable, often used to denote time in equations and graphs. It is also commonly found in programming languages, where it may serve as a placeholder or identifier. The letter "t" appears in many languages and is essential for forming numerous words and expressions.