The meaning behind the 'X' in 'Produce X 101' has been explained on 'Produce X 101 The Beginning.' 

On the special broadcast ahead of the new season, IZ*ONE, the winning group of the previous season, made an appearance in support of the trainees. 

Kang Hye Won asked MC Hongki, "Why is it called 'Produce X 101' and not just 'Produce 101' this time?" Hongki explained, "The 'X' in 'Produce X 101' symbolizes the trainees' unlimited potential growth. It also means 'Xtension,' meaning they will expand globally. Not only will they succeed domestically but also on Billboard and become a global group."

The first episode of 'Produce X 101' is set to air on May 3.