21st Birthday Wishes Quotes: Turning 21 makes you feel mature when you realize you really are not a teenager anymore. Of all the birthday’s (every year) the 21st is the most significant. The 21st birthday is a milestone in every college student’s life. This is a age when you entered into maturity period and things to be looked serious. So the age deserves to be celebrated with bang. Welcome your loved one 21st birthday with lots of fun and joy. But a birthday is incomplete without wishes so congratulate your best friend or girlfriend or boyfriend on his/her 21st birthday.