Here's why:
* Common Noun: "Teens" is a common noun, referring to a general group of people. Common nouns are not capitalized unless they are at the beginning of a sentence.
* Not a Proper Noun: "Teens" is not a specific name or place, like "The Beatles" or "California."
Example:
* Incorrect: "The Teens of today are facing unique challenges."
* Correct: "The teens of today are facing unique challenges."
Exception:
* Proper Noun: If "teens" is part of a specific name or title, such as "The Teen Choice Awards," then it should be capitalized.