Taeyeon began working on a solo album in late 2014, believing her "right time" had come. She previously was afraid of not being ready for a solo debut, but her eight-year career gave her enough experience to be "well-prepared".  The final product, an extended play titled I, was released in October 2015.  The EP peaked at number two on South Korea's Gaon Album Chart.  It became the sixteenth best-selling album of 2015 in South Korea, with sales of 119,576 copies.  It additionally peaked atop the US Billboard World Albums.  The commercial success of I, according to Yonhap News Agency, was the main contributor to SM Entertainment's leading music sales during the fourth quarter of 2015.  The lead single, which features rapper Verbal Jint, peaked at number one on the Gaon Digital Chart and has sold over one million digital units.  To accompany her solo release, she held a series of small concerts titled Taeyeon's Very Special Day.  Her concurrent reality show, OnStyle's Daily Taeng9Cam, was the third most popular idol program of 2015 in South Korea.  Taeyeon was also named Best Female Artist at the 2015 Mnet Asian Music Awards, and at the 2016 Golden Disk Awards.