Britney Spears visits the BBC Radio 1 in London, Sept. 28, 2016.

Britney Spears performs onstage during the 2016 MTV Music Video Awards at Madison Square Garden, Aug. 28, 2016, in New York City.

This photo was posted to Britney Spears' Instagram account on May 31, 2016 with the text, "Feel it already... Gonna have a great day at my desk!"

Britney Spears posted this photo on her Instagram account with the caption: "A very much needed haircut," May 29, 2016.

Britney Spears performs Britney Spears: Piece of Me Remixed. Reimagined. Still iconic. At Planet Hollywood Resort & Casino on Feb. 26, 2016 in Las Vegas.

Britney Spears, recipient of the Millennium Award, poses in the press room during the 2016 Billboard Music Awards at T-Mobile Arena, May 22, 2016, in Las Vegas.

Britney Spears attends the 2016 Billboard Music Awards at T-Mobile Arena, May 22, 2016, in Las Vegas.

Britney Spears is seen on stage during the 2016 Billboard Music Awards held at the T-Mobile Arena, May 22, 2016, in Las Vegas.

Britney Spears posted a photo of herself to her Instagram account on April 5, 2016 with the caption, "Happy Monday everyone!"

Britney Spears visited Hawaii with her sister, Jamie Lynn, March 30, 2016.

Britney Spears posted this image of herself on her Instagram account, Jan. 12, 2016, with the message: "Yoga yoga...feelin better and getting back on the mat!!"

Britney Spears shared this image to her Instagram account, Dec. 8, 2015.

Britney Spears posted this photo with the caption, "Two blondes... Too much fun. Loved hanging with you last night @katehudson!" on Oct.4, 2015.

Britney Spears enjoy of rides and fun with her niece and brother, not pictured, Sept. 27, 2015, in Los Angeles.

Britney Spears posted this photo to her Twitter on Aug. 24, 2015 with the caption, "Backstage moment... Hair, Wings."

Britney Spears poses with Maddie Briann Aldridge, Sean Preston Federline, and Jayden James Federline in the press room at the Teen Choice Awards 2015 at Galen Center, Aug. 16, 2015, in Los Angeles.

Britney Spears is seen, July 24, 2015, on the beach in Hawaii.

Britney Spears posted this photo, July 23, 2015, with the caption, "Aloha!"

Singer Britney Spears and Charlie Ebersol attend the 2015 Billboard Music Awards, May 17, 2015, at the MGM Grand Garden Arena in Las Vegas.

Britney Spears posted this photo to Instagram on April 20, 2015 with the caption, "Look what I got over the weekend! Thank you Best Of Las Vegas, my dedicated team & POM crew, @phvegas, and all of YOU!"

Britney Spears celebrates Celebrate Easter with her boys by taking them for lunch in Argoura Hills, Calif., April 5, 2015.

Britney Spears enjoys a day by the pool in Hawaii, March 22, 2015.

Britney Spears grabs sushi with her dad at Honshu Sushi dressed down in a silk top and jeans, Feb. 4, 2015, in Los Angeles.

Britney Spears is seen in this photo from video posted to her Instagram, Jan. 21, 2015, with the caption, "Putting in work in preparation for my tryout for the US Synchronized Swimming team. Rio here I come..."

Britney Spears posted this photo to Instagram with the caption,"Surf all day, dance all night. See you tonight Vegas!" on Oct. 15, 2014.

Britney Spears is photographed out and about in Westlake Village, Calif. on Oct. 6, 2014. It has been 16 years since her first hit single, "Baby One More Time."

Britney Spears posted this photo on Sept. 17, 2014 to Instagram with the caption, "Tons of X's and O's to my BFF."

Britney Spears posted this photo to Instagram with the caption, "Studio today! Yay!" on Sept. 4, 2014.

Britney Spears gets some shopping done in Westlake where she stopped by Kate & Lace Lingerie and Swim in Westlake, Calif., Aug. 26, 2014.

Britney Spears performs during her "Britney: Piece Of Me" show at the Planet Hollywood Resort and Casino in Las Vegas, Nevada on Aug. 16, 2014.

Britney tweets a photo of her new brunette self, Feb. 8, 2014.

Britney Spears performs at Planet Hollywood in Las Vegas, Feb 4, 2014.

Britney Spears posted this image to her Twitter account Dec. 26, 2013 with the caption "Can't believe the 1st show is almost here!!! #PieceOfMe"

Britney Spears posted this image to her Twitter account Dec. 26, 2013, with the caption "I've got chills. Last dress rehearsal for friends and family before opening night tomorrow. #1DayTillShowtime"

Britney Spears celebrates her official arrival at Planet Hollywood Resort & Casino, Dec. 3, 2013 in Las Vegas, Nevada.

Britney Spears attends the iHeartRadio Music Festival at the MGM Grand Garden Arena on September 21, 2013 in Las Vegas.

Britney Spears unveiled the new video for her collaboration with will.i.am, "Scream And Shout", Nov. 28, 2012.

L.A. Reid, Demi Lovato, Simon Cowell and singer Britney Spears attend the Fox 2012 Programmig Presentation Post-Show Party at Wollman Rink - Central Park on May 14, 2012 in New York City.

Jason Trawick and Britney Spears celebrate their engagement at Planet Hollywood Resort & Casino on December 16, 2011 in Las Vegas, Nevada.

ABC News' Diane Sawyer talked to Spears in New York for a "Primetime" special that aired Nov. 13, 2003.

Britney Spears celebrated her 27th birthday in December 2008 by performing at the Big Apple Circus tent in New York City on "Good Morning America." Britney kicked off her comeback tour, "The Circus Starring Britney Spears," three months later at the New Orleans Arena on March 3, 2009, her first arena concert since 2004.

Spears posed with "GMA's" Robin Roberts and the Gatorettes on Mardi Gras week in February 2006 when "Good Morning America" broadcast live from New Orleans.

Britney Spears revealed a lot for the April 2011 issue of OUT magazine. Posing in a leotard, the pop star shared her thoughts on homosexuality, saying that whether her sons turn out to be gay or straight, she'll always "love my boys no matter what."

Spears also told OUT that someone once told her the iconic "…Baby One More Time" video "should be me as a superhero fighting a giant robot monster."

Spears also revealed her icons, saying she admires "Sarah Jessica Parker's career and her shoe collection" and said that she thinks she was Audrey Hepburn in a past life, "because she was a trend setter."

A classic black-and-white scene from Britney Spears' upcoming MTV documentary, "For the Record," Nov. 30, 2008. "So much has gone on over the last couple of years and there's a lot that people don't know about me that I want them to know," Spears told MTV News in a statement about the special. "I wanted to make this film because I started to feel like I wasn't being seen in the light that I wanted to be seen in. This is an opportunity to set the record straight and talk about what I've been through and where I'm headed."

Spears bewildered and entertained photographers with her constant antics and lack of clothing. Out and about one summer afternoon, Spears didn't have her swimsuit, but she didn't let that stop her from taking a dip. The struggling singer got a little wet and wild in her undergarments and flashed some photographers a very unflattering view of her bare behind, July 18, 2007.

NSYNC, Aerosmith and Britney Spears all perform during halftime at Super Bowl XXXV between the Baltimore Ravens and New York Giants at Raymond James Stadium in Tampa, Florida on Jan. 28, 2001.

Britney Spears & Justin Timberlake of NSYNC at the Shrine Auditorium in Los Angeles, CA.

Britney Spears appeared on "Sabrina the Teenage Witch" alongside Melissa Joan Hart, pictured above. In the episode, entitled "No Place Like Home," Sabrina considers moving to Paris after her junior year of high school. It aired on Sept. 24, 1999 on the ABC Television Network.

Britney Spears and NSYNC are seen in this undated photo at a rehearsal for the 1999 MTV Video Music Awards.