They came all the way from Australia or directly from Brooklyn: lugging their instruments through the streets, lending equipment to one another, glad-handing any interested listener, selling do-it-yourself CDs and vinyl and, by and large, striving to garner enough new attention and contacts to make all the effort worthwhile. Bands like the xx and Arcade Fire have emerged from CMJ with exponentially expanded reputations; the prospect is enough to draw new hopefuls by the hundreds.  CMJ has stood for College Music Journal and then College Media Journal; it started as a college-radio newsletter and chart compiler. Its core is still music aiming for college radio airplay and, more recently, exposure through the countless Internet outlets for everything loosely described as “indie.” Which, in the 2010s, is virtually anything shut out of commercial radio formats — for being too idiosyncratic, unfashionable, ahead of its time, unpolished, arty or just off-base — alongside many contenders who’d be perfectly delighted with a shot at the Top 40 or, perhaps, a licensing fee to lend their music to a commercial. Indie or not, CMJ is about careers.  In my peregrinations through this year’s CMJ I saw about 100 acts, less than 10 percent of the possibilities. So it could be mere coincidence that I kept noticing the inroads that electronic dance music has made in an indie realm that used to equate the authentic with the handmade. It wasn’t just the laptops, samplers and electronic drum pads that kept turning up onstage alongside the guitars. And, luckily, it wasn’t merely an onslaught of the blunt four-on-the-floor beat that D.J.’s turned producers now use to propel radio hits — although that was there too from acts like Icona Pop, two women from Sweden who settled scores with ex-lovers in chirpy, pounding, singalong-ready choruses, but who also deployed a tableful of electronic gadgetry to remix their songs on the spot.  Just as often the dance-music effect was an undogmatic blend of live and machine-generated rhythms, an embrace of sounds that are difficult or impossible to produce on physical instruments, a willingness to trance out with repetition, and a sense of song structure resembling a dance-music set: prizing smooth transitions and not looking back. That showed up in songs by Duologue that strung together verses, refrains, guitar patterns, electric-violin lines and percussion breaks, and in the plinking, floating, Minimalistic reveries of two groups featuring the singer Raphaelle Standell-Preston: the band Braids and her electronic duo, Blue Hawaii. Another intriguing art-rock band, Hundred Waters, has extrapolated its own kind of convoluted songs from Bjork’s mixture of the pastoral and the futuristic.  Gabriel Bruce, a songwriter whose deep baritone and morose, death-haunted lyrics might have led him toward Leonard Cohen territory in another era, had electronic beats and backup dancers instead. Gold Minds, an Australian band, brought tuneful pop approachability to the kind of dance rock that appeared in the 1980s, revving it up with buoyant Caribbean syncopations. Savoir Adore, from Brooklyn, combined two sounds of optimism: surging folk-rock chords and the solid foundation of an electronic beat.  CMJ included electronica explorers like Jerome LOL, who threaded jazz basslines through his mixes, and Holy Other, who concocted deep, eerie dirges. Maria Minerva, originally from Estonia, offered electronica as demented performance art; while she generated loops and samples — chords, rhythms, haze — she crooned in a slurred, obsessive singsong, repeating lines like “I see all the lonely people looking at the other lonely people.” But there was far more dancing for the marchlike, midtempo instrumentals and clear-cut tunes of Com Truise, a duo of electronics and drums.  Electronica experiments infused some of CMJ’s hip-hop. Instead of straightforward looped beats Mykki Bianco rapped some of his down-and-dirty free associations over a deep, eardrum-pressuring subwoofer drone and stray blips and crackles. Ratking — two rappers and two electronics players — delivered its rhymes in an nearly impenetrable fog of crackly, sputtering noise. Death Grips also placed a thick electronic squall around live elements: rhymes from Stefan Burnett and the live drumming of Zach Hill from the group Hella.  Not all of CMJ’s hip-hop was so willfully difficult; for more mainstream rappers, CMJ is just another media platform. Angel Haze rocketed through her most belligerent tough-gal rhymes, slinging polysyllables at top speed. Killer Mike, in a vigorous set shot for MTV, veered between making political statements and exulting in what he cheerfully called “vices.” And Kitty Pryde offered cute, comedic expositions of unrequited crushes.  Yet as always, CMJ was a bastion of guitar-driven rock; college radio is a holdout against programmed, Auto-Tuned current pop, and it’s often a bastion of revivalism. Metz, a three-man band from Canada, steamrollered through the festival, blasting brawny punk and metal guitar riffs that generated the festival’s most enthusiastic buzz. The band DIIV brought nimble intricacy, reviving the precise, cascading, pick-and-strum guitar patterns of bands like the Feelies and New Order.  Savages reclaimed the frenetic, dissonant drones and crescendos of bands like Siouxsie and the Banshees, with the ascending wail and piercing glare of its lead singer, Jehnny Beth. The ZZZ’s, a three-woman group from Japan, also revived some decades-old strategies: the crisp, conceptual riffs of no wave. Poor Moon revived genial, reassuring 1970s folk-pop. And reaching further back, toward the 1960s, Wooden Indian Burial Ground surged through blues-riffing garage psychedelia, with vicious guitar tones and a handmade analog synthesizer, while Twerps offered kindly, strum-along songs proffering friendship and love.  CMJ was also hospitable to more mainstream contenders. Sky Ferreira, who performed day and night throughout the festival, had pouty, pop-rock love songs clearly aimed for a broad audience. Little Green Cars, an Irish band, arrived in the wake of Mumford & Sons, sharing that band’s American label. They too have earnest songs about love and devotion, delivered with folky strumming and hearty vocal harmonies, but with more of a 1960s flavor than Mumford. Merchandise — a band that, despite its name, has been giving its music away online — summed up this year’s CMJ more uneasily. It is emerging, ambivalently, from the Tampa punk underground, although its music is closer to the brooding, surging, crooning post-punk of the Smiths. It made its CMJ debut outside the official CMJ, at a concert presented by the online magazine Pitchfork, playing a ragged set to a crowd with a lot of conversation in the back. Its beat was electronic: a drum machine. And Carson Cox, its lead singer, offered grudging encouragement to the crowd eager to claim the next big thing. “You can move,” he said.  This article has been revised to reflect the following correction:  An earlier version of this article misidentified the country Maria Minerva is originally from. It is Estonia, not Iceland.  An earlier version of this article misidentified the country Maria Minerva is originally from. It is Estonia, not Iceland.
Bonanza and glut, harbinger and revival, party and business meeting, auditions and acclamations, a random sample of whatâs new: the CMJ Music Marathon is all of them at once.