When Holger Czukay died last year at the age of 79, there was a sense among music lovers that it was a momentous transition: the passing of a true giant. Few, though, could articulate exactly why or how. What did Czukay and his band Can do to help invent the sounds that pass through your earbuds every day, no matter what genre you're into?

Krautrock might be the quintessential rock nerd's microgenre. Its premier purveyors, Can, never toured the U.S., and released songs with only intermittently intelligible lyrics. They had commercial success, especially in Germany, but nothing that you'd consider a real international "hit." Even among music fans, you're ahead of the game if you can associate Can with the term krautrock, with bonus points if you can actually name one of their songs, or any other krautrock artists.

Yet, the genre's influence is vast. From hip-hop to EDM to rock, virtually any music incorporating electronic elements owes some debt to krautrock. Can, Kraftwerk, and Neu! contributed essential bricks to the foundation of two decades of popular music: much of the pulse of disco came from krautrock, and so did the drum machines and pealing synths of the '80s. It took Donna Summer, Prince, and U2 to turn krautrock's ideas into common currency, but without the West German music scene of the late '60s and early '70s, untold thousands of hit songs might have sounded very different — or not existed at all.

Two recent books take a 21st century look at krautrock and its legacy: Ulrich Adlet's academic volume Krautrock (2016), and the doorstop volume All Gates Open: The Story of Can (2018). The latter is actually two books in one: the first is a conventional band biography written by Rob Young, while band member Irmin Schmidt takes the helm for the second, which is a collection of conversations and recent diary entries.

Both books acknowledge that it's taken decades of hernia-inducing critical acclaim to lift krautrock to even the dim level of familiarity it now enjoys. The heyday of krautrock was almost over when the term was popularized by BBC host John Peel, who may have found the coinage when it was used as the name of a song by the krautrock band Faust. From the early '70s, British musicheads praised krautrock, and the newly-founded American publication Pitchfork picked up the torch in the '90s as part of its deep-dive ethos. By the time Czukay died, serious fans of popular music at least knew that they were supposed to care deeply about krautrock.

Krautrock was created by the German equivalent of baby boomers: born shortly before World War II (as in the case of Czukay and Schmidt), or during or shortly after the conflict, these musical adventurers came to the late '60s sharing many of their American counterparts' countercultural ideas, and familiar with cutting-edge rock artists like JImi Hendrix, but also interested in the electronic experimentalism of composers like Karlheinz Stockhausen.

Stockhausen, who inspired the Beatles' tape-loop experiments and mentored both leaders of Can, made avant-garde composition relevant to popular musicians who were interested in strong rhythms, new recording techniques, and ultimately electronic sonorities. For a sense of how this played out in krautrock, take a listen to Can's song "Spoon," which inspired the name of the band Spoon. It opens with a drum machine, and then a synth hook comes in. Mundane stuff...15 or 20 years later. This was 1972.

If that voice doesn't sound very "kraut," that's because it's not: it's the voice of Kenji "Damo" Suzuki, a Japanese singer who was the most important of the several vocalists the band went through. At the top of Adelt's academic agenda is to make the case for krautrock as more than stereotypically German: the genre's purveyors were very deliberately global-minded, even utopian in their eclectic tastes. Yet another musical tree watered by krautrock was that of new age music, with its heterogeneous (some would say sloppy) mixing of ethnic sounds into a sort of cosmopolitan star-soup.

Jazz-loving players who ultimately claimed such esoteric distinctions as the first band to improvise a drum machine solo, Can were at the center of what came to be regarded as krautrock — but they weren't the only ones hanging out there. The other two big krautrock names to know are Kraftwerk and Neu!

Neu! were a minimalist duo who helped pioneer a configuration that's now become commonplace: they had only a guitarist and a drummer, no bassist. The clean, pulsing sound felt very German, but the band were reluctant to embrace that label, preferring to emphasize their American and African influences. "I am not a big fan of Germany," said drummer Klaus Dinger.

Then there were Kraftwerk, who would become far and away the genre's best-known band even though their breakthrough album, Autobahn (1974), really marked the end of jazzy Can-style krautrock and the beginning of an entirely electronic sound that carried the concept almost to the point of caricature, with the band members standing at consoles and cuing computer-generated graphics. With songs about robots and precision-engineered highways, they certainly weren't shying away from being seen as German.

The influence of krautrock spread through two major vectors. First, there was Giorgio Moroder. The Italian producer established his Musicland studio in Munich, launching the career of Donna Summer when the then-impoverished single mother responded to an advertisement for an African-American female singer. Not only did her work with Moroder launch her to superstardom (she adapted her stage name from the surname of her German husband, Helmuth Sommer), songs like the 17-minute "Love to Love You Baby" lit a million dance floors under disco beats that came, as it were, straight out of the Can.

The other channel was David Bowie, who had just established himself as a major international star when he moved to Germany and collaborated with Brian Eno on what became known as his "Berlin Trilogy": three albums (1977-79) that completed the melding of krautrock's ambient electronic textures with Bowie's powerful songwriting and unparalleled sense of visuals and character. Adelt draws a line straight from Bowie's Berlin years to Talking Heads, the Human League, U2, Nine Inch Nails, Radiohead, and LCD Soundsystem.

On top of all that, there was the genre's influence on hip-hop. Afrika Bambaataa prominently sampled Kraftwerk, and Adelt quotes Jam Master Jay of Run-D.M.C. singing the praises of krautrock. "These guys proved to me you don't have to be where I'm from to get the music. That beat came from Germany all the way to the 'hoods of New York City."

If you now have a greater appreciation for krautrock, that still doesn't necessarily mean either of these particular books are for you. Adelt's volume dives into everything from the intersection between krautrock and film (Werner Herzog, Wim Wenders, and Sofia Coppola are among the directors who have turned to krautrock for soundtracks) to how krautrock evolved in the era of new wave. The Can book is...well, it's a 572-page book about Can.

One of the book's most intriguing passages has co-author Young visiting Germany's RocknPop Museum, where Can's legendary Inner Space studio has been reconstructed. Even Young, who after all is putting the finishing touches on a huge volume about Can, doesn't know what everything is for.

There's a hexagonal wooden table on wheels called an "Abhörtisch" that seems to have been some kind of group monitoring hub for multiple headphone inputs. Cables and connectors hang coiled on a massive wall rack. Collections of percussion and exotic instruments lie around on tabletops: cowbells, bamboo rattles, brass finger-cymbals, an African talking drum, bells from Vietnam, Indonesia, China and Japan. Hand-painted castanets surely picked up from a tourist stall in Ibiza. Pan pipes, wood flutes and tambourines: the instruments of Greek mythology. A gong, its iron hub engraved with a pentagram. The tools of the musician, waiting to be flooded with magic.

A few pages later, Young poetically summarizes the legacy of krautrock, writing that Can gave permission for music "to embrace the machine, to thieve the Promethean fire of technology and make it human."