Synthesizers had been slowly percolating into popular music since the late ‘60s, and over the ‘70s they’d serve as a cosmic enhancement on countless prog-rock records. But through the robo-rock innovations of Kraftwerk and Giorgio Moroder’s groundbreaking electro-disco productions for Donna Summer, the synth was elevated from embellishment to essential feature. And as the technology was embraced by adventurous punks and aspiring radio stars alike, synth-pop became the defining musical style of the ‘80s. It was the agent through which post-punk artists like New Order and The Human League infiltrated the wedding-DJ canon, as well as the shiny packaging that attracted the stateside masses to European exports like a-ha. But as much as it signifies a particular moment in music history, synth-pop truly transcends era: Thanks to savvy revivalists like CHVRCHES and Future Islands, it’s become the lingua franca of modern indie.