- Birthname : Im Yoon Ah
- Name Meaning : Innocent Child
- Nickname in SNSD : Charming Girl
- Other Nicknames : Little Deer, Retard, Flower Deer, Powerful Yoona, Bravery Yoona, YoonABC
- Birthday : May 30, 1990
- Blood Type : B
- Height : 166 cm
- Weight : 47 kg
- Position : 3rd Lead Dancer, Supporting Vocalist
- Favourite Numbers : 93
- Speciality : Acting
- Years of Training : 7 years 2 months
- Discovery: 2002 SM Saturday Open
Casting Audition
- School(s): Dongguk University,
Daeyoung High School
- Favourite Song from Girls Generation : Complete
