Chaeryeong was a contestant on K-pop Star 3 in 2013. In 2015, she went to compete in JYP Entertainment's survival show Sixteen. However, she did not make the cut to become a member of the winning girl group, Twice. In 2018, Ryujin was a contestant on JTBC's survival show Mix Nine. She placed first among the girls in the competition, but lost to the boys for the overall winners. Yeji was a contestant on SBS' The Fan, but was eliminated in episode 5. All of the members, except Lia, appeared in Mnet's reality showStray Kids as a project group against the boy group Stray Kids in 2017.
2019: Debut with ''It'z Different'' and ''It'z Icy''
On January 21, JYPE announced that they would be debuting a new girl group, the first since Twice's debut in 2015. The label's official channel uploaded a video trailer revealing the five members. On February 12, the group released their debut single album, It'z Different, with its lead single "Dalla Dalla". The song incorporates elements from EDM subgenres, such as future house and bass house. Its empowering lyrics have been well received by the audience. The group scored one of the biggest Billboard debuts for a new K-pop act in years, single "Dalla Dalla" entered at No. 3 and peaked at No. 2 on the World Digital Song Sales chart. The shape-shifting confidence anthem sold 2,000 downloads in the U.S. for the week ending February 14, according to Nielsen Music, making it the best-selling K-pop song in America that week. "Want It?," released alongside the single "Dalla Dalla," debuted at No. 8 selling 1,000 downloads. "Dalla Dalla" also debuted as the second most popular song on YouTube. Billboard confirmed that the music video surpassed 17.1 million views within 24 hours of its release and broke the record for the most viewed K-pop debut music video within 24 hours. On February 21, eight days after their debut, Itzy received their first music show win on M Countdown and became the fastest girl group to achieve their first music show win. "Dalla Dalla" also holds the record for the fastest K-pop debut music video to reach 100 million views. Itzy's debut EP, titled It'z Icy was released on July 29, 2019 along with an accompanied music video for its lead single titled "Icy". On September 22, JYPE announced Itzy's showcase tour titled Itzy Premiere Showcase Tour "Itzy? Itzy!". A showcase tour kicked off in Jakarta on November 2 and then take the act to different cities in Asia throughout the end of 2019 before heading to the United States for five shows in January 2020. In November 2019, "Dalla Dalla" surpassed 100 million streams on Gaon Music Chart, becoming the group's first platinum certification. It is also the first debut song by a K-pop group to earn a platinum certification from the Korea Music Content Association since the introduction of the certifications in April 2018. The single also ranked No. 8 on the list of "The 20 Best K-pop Songs of 2019" by Dazed, which stated that the group "keep a steady hand on the rudder using the fun touches even with the visual and sonic chaos going on around" and "the ones to give K-pop a fresh boot up". The music videos of "Dalla Dalla" and "Icy" entered the list of South Korea's most popular music video on YouTube, at No. 2 and 7 respectively. At the end of the year, Itzy was recognized with several Best New Female Artist awards, including the 2019 Melon Music Awards and the 2019 Mnet Asian Music Awards.
2020: United States showcase tour, ''It'z Me'' and ''Not Shy''
Itzy started the year with the continuation of their showcase tour in the United States, starting on January 17 in Los Angeles. On March 9, 2020, Itzy released their second EP, It'z Me, and its lead single "Wannabe". The EP debuted at number one on South Korea's Gaon Album Chart, making it the group's first number one album in the country. It also debuted at number 5 on Billboard's World Albums chart, their highest position on the chart. On July 30, 2020, ITZY announced a release date for their upcoming music video and album Not Shy.
