What accomplishment did Justin Guarini attain?

Justin Guarini is best known for his accomplishment of being the runner-up on the first season of American Idol in 2002. While he didn't win the competition, his performance and the popularity he gained from the show launched his career in the entertainment industry.

He has since:

* Released several albums

* Starred in various Broadway productions

* Appeared in television shows and films

* Hosted radio shows

While not winning American Idol, he still achieved significant success in the music and entertainment industry.