This year's iHeartRadio Music Festival takes a more mainstream direction than in previous years. (festival.iheart.com)

iHeartRadio always offers up quite a lineup, with lots of big names in a variety of genres, including everything from rap and pop to country.

In its inaugural year (2011), superstars like Jay Z, Lady Gaga, Carrie Underwood, and Coldplay performed.

However, last year's festival may be most remembered for the infamous "Green Day incident" when lead singer Billie Joe Armstrong launched into an onstage rant that ended with the singer smashing his guitar and led to his checking into rehab soon after.

The reason for Armstrong's rant remains a mystery, but some believe that the punk rock band's set was cut short in order to accomodate Usher, who came on right before Green Day and whose set ran 20 minutes long. 

This year, Clear Channel is introducing some new features to the iHeartRadio Festival formula, including an additional stage called the Festival Village headlined by none other than the master twerker herself: Miley Cyrus.

Cyrus will be joined at the Village by other big pop names like Avril Lavigne, The Wanted, and more.

While last year's festival leaned heavily towards rock and R&B with headliners like Bon Jovi, Aerosmith, and Mary J. Blige, this year offers a more mainstream pop lineup with artists like Bruno Mars, Ke$ha, and Katy Perry taking over the main stage.

The iHeartRadio Music Festival takes a step away from the traditional festival experience where the point is to discover new, up-and-coming or underground talent rather than listen to already established acts. However, Macy's holds an annual Rising Star competition, with this year's winner being pop rock band The Summer Set from Scottsdale, Arizona.

iHeartRadio Music Festival 2013 will be broadcast live over all Clear Channel radio stations today and tomorrow. It will also be aired on the CW next week on September 30 and October 1.

Today's headliners include Katy Perry, Queen and Adam Lambert, Keith Urban, Elton John, and will begin at 7pm PT (10pm ET).

For a full lineup of artists on the main stage, click here. For a list of artists performing at the Festival Village, click here.

Reach Staff Reporter Michelle Tiu here or follow her on Twitter.