The Atlanta-based Zac Brown Band have grown into a mini-empire since their leader began gigging under that name in 2002. Their take on country music is far-reaching and full of surprises, drawing on traditional Nashville songwriting ideals as effortlessly as cutting-edge pop; their live shows have the epic length of jam-band freakouts and the cross-generational appeal of stadium-rock barnburners; and their extra-musical interests, which include a line of portable speakers and a camp for deserving kids, show their boundless ambition. After growing their fanbase on the road during the 2000s, ZBB broke through in 2008 with “Chicken Fried,” a love song to Southern culture. A slew of country-radio chart-toppers followed, including the laidback “Toes,” the harmony-rich Alan Jackson collab “As She's Walking Away,” and the sun-kissed Jimmy Buffett duet “Knee Deep.” As the 2010s progressed, ZBB dug even deeper into their collective musical knowledge and savvy, recording a 2013 EP with Foo Fighters leader Dave Grohl, duetting with Soundgarden frontman Chris Cornell, and welcoming electronic artists like Skrillex and Poo Bear into the fold. Zac Brown Band’s journey has been full of unexpected twists over the group’s lengthy existence, but their listeners have been rewarded with striking expansions of what the term “country music” can mean.