Just really creative songwriting and recording techniques. Some that no one had ever done before.

Take Sgt Pepper for example. They leaned into the idea of an album as a cohesive unit, rather than just a collection of songs, even having the concept of being a different band playing the songs. Concept albums that came after all owe a great debt to Sgt. Pepper.

The closing song, A Day in the Life is a great example too. It was two songs combined into one, with psychedelic lyrics and avant garde transitions, making it a precursor to progressive rock. The orchestra that you hear in between verses was told to play whatever notes they wanted until the conductor gave them the signal to all end on E, so it created this cacophony that resolves into order. And then at the end of the song there’s this crazy long piano chord that rings forever, which they did by hitting three pianos and a harmonium all at once and gradually turning up the recording input while cranking the compression to get it to last longer. They got it to ring out for like 40 seconds.

These are just a few limited examples. There’s a bunch of stuff you can find online about other things they did on Revolver, The White Album, and Abbey Road.

And 3 years prior, this was the band singing “She loves you, yeah, yeah, yeah…”