Nostalgia is a funny thing. Some people consider it a dirty word. Others unashamedly embrace it and simply revel in their past, perhaps in hopes of reliving a moment from their formative years.

For Vans Warped Tour, this year’s edition is a throwback to the festival’s glory days with a roster that includes Yellowcard, Sum 41, New Found Glory, the Story So Far, the Maine, and Mayday Parade, to name a few.

“It’s great to go back to Warped to reconnect,” tour founder Kevin Lyman told the Dig. “This year, a lot of those [veteran] bands were available and wanted to do it. It kind of got on a roll where we got a couple, and these other bands wanted to be out there with their friends.”

In its 21st year, Warped is the nation’s longest-running traveling festival, bringing 12 hours of nonstop music on like a billion stages to outdoor venues across America every summer. Throughout its history, the tour has been bold, eclectic, inclusive, and unafraid to take chances. It has become a community unto itself and is a place where bands look out for each other and pass along valuable lessons to the next breed of road warriors.

“Last year, I had a very young lineup,” Lyman says. “It was fine, but I need some of these older bands to be out there as mentors to these younger bands. I’m really excited to have some friends out there this summer.”

Also among the tour’s elder statesmen this summer is Worcester’s own Four Year Strong, which is making its fifth run on Warped.

“I like it for a lot of reasons,” Four Year Strong’s Alan Day says. “The shows are always great. It’s like summer camp. You get to see your friends every year. The kids are always super excited to see all their favorite bands all at once. Sometimes it’s hot and you get tired, but we’re super stoked.”

Day also notes that Lyman and his Warped curators “adapt to the times.” Over the years, they’ve mixed in everything from death metal to pop (Katy Perry and the Black Eyed Peas famously played the tour) to backpack rap to stoner reggae (Pepper returns this year) to electro DJs.

In addition to the roster of vintage pop punk bands, this year’s edition also includes glam rockers Falling In Reverse, Hollywood electro band Ghost Town, ska heroes Less Than Jake and Reel Big Fish, and current emo stars Sleeping With Sirens and Knucklepuck. For the headbangers, there’s Motionless in White, Chelsea Grin, Buffalo stalwarts Every Time I Die, Boston’s Vanna, Veil of Maya, Whitechapel, and I See Stars.

For Day, Warped was essential to exposing the band to massive crowds during the group’s early years. It’s working on new material and will be playing some new songs in Mansfield.

“It’s always the best show of the summer for us,” he said. “We’ve been very fortunate to have a very loyal hometown fan base. We’re definitely lucky.”

There’s always a charitable component to the tour too. Last year, it was a food drive. This year, it’s Voices of the Innocent, a sexual assault awareness campaign. And 25 cents from every ticket sold goes to charity, which has added up as Warped is set to sell its 10 millionth ticket this summer.

“I look at Warped Tour as it has three things: bring good music, do good things for the community, and we want to educate people on being good citizens and how to go to a festival and enjoy yourself and just have a good day,” Lyman said. “It looks like it’s going to be a good summer.”