Lady Gaga has hit a new Twitter milestone - she has reached 20 million followers and remains the most popular person on the social network.
Pop star Justin Bieber, who recently celebrated his 18th birthday, retains his second place spot with 18 million followers. Fellow pop stars Katy Perry and Shakira are in third and fourth place with 15.7 million followers and 14.5 million followers, respectively. Pop and R&B singer Rihanna is No. 5 with 14.4 million.
Lady Gaga has used her social networking accounts on Twitter, Facebook and Google Plus to promote her music as well as her charity initiatives. The pop star and gay rights activist launched her Born This Way Foundation, which aims to help raise awareness about the problem of bullying in schools, last month.
She has also gone further than many celebrities by tapping into online gaming. Last year, Lady Gaga-branded objects were incorporated into the popular Zynga-made Facebook game Farmville as part of a marketing campaign to promote new music from her album "Born This Way."