She recorded "Like A Star" (featuring The One), having the song peaked at number one on Gaon Digital Chart after its release.Ahn recalled his impression of the latter song: "I was surprised at how well Taeyeon could sing.
A finales del 2003, fue enviado a los dormitorios con los otros alumnos y empezó a asistir al entrenamiento junto con los demás.Ese mismo año, hizo su primera aparición en los medios de comunicación en el vídeo musical de Dana (miembro de The Grace) "What Is Love".She previously was afraid of not being ready for a solo debut, but her eight-year career proved to help her gain the experience to be "well-prepared".After her record label's musical focus started steering towards EDM, her follow-up EP titled Why (2016) also saw that incorporation into its track list.Her other 2014 releases included "Colorful" for JTBC's campaign "The World Is More Beautiful Because We're Different" and "Love, That One Word" for the SBS's drama You're All Surrounded; the latter entered Top 10 on both Gaon Digital Chart and K-Pop Hot 100.
Taeyeon began working on a solo album in late 2014, believing her "right time" had come.
It peaked at number two on South Korea's Gaon Album Chart and its title track sold over one million digital copies.
Her second extended play, Why (2016), charted at number one and yielded two Gaon Digital Chart top-ten singles "Starlight" and "Why".
That same year, she won first place at the SM Youth Best Competition and officially received a contract from SM Entertainment.
The training process was so tough that it nearly made her quit at one point; she continued, however, and debuted as a member of girl group Girls’ Generation in August 2007.
She was cast in a lead role in the musical Midnight Sun (2010), an adaptation of the Japanese novel of the same name (2006).