- Birthname : Seo Joo Hyun
- Name Meaning : Worthy Pearl
- Nickname in SNSD : The youngest
Princess
- Nicknames : Seororo, Innocent Seohyun, KeroHyun, Youngest child, Milk Seo Joo
- Birthday : June 28, 1991
- Blood Type : A
- Height : 168 cm
- Weight : 48 kg
- Position : 3rd Lead Vocalist
- Favourite Numbers : 64
- Hobbies : Piano, Watching Keroro
- Speciality : Chinese, Piano
- Years of Training : 6 years 6 months
- Favourite Song from Girls Generation : Kissing you
- Discovery: 2003 SM Casting System
- School(s): Daeyoung High School
