Conversation so far:
What is progressiveness?
Elements contributing to the progressive label include: lyrics were more poetic, technology was harnessed for new sounds, music approached the condition of art, and the studio became the focus of musical activity
What is psychedelia?
Psychedelic music (sometimes called psychedelia is a wide range of popular music styles and genres influenced by 1960s psychedelia, a subculture of people who used psychedelic drugs
How did the Beatles contribute to progressiveness?
The Beatles' experimental timbres, rhythms, tonal structures, and poetic texts on Rubber Soul and Revolver encouraged a legion of young bands that were to create progressive rock“.
What instrument did the Beatles spark a musical craze for?
Played by George Harrison, the sitar part in Rubber Soul's Norwegian Wood launched a craze that Indian classical musician Ravi Shankar termed the great sitar explosion“
When did the Beatles start using droning guitars?
The Beatles themselves with Ticket to Ride incorporated droning guitars to mimic the qualities of the Indian sitar.
Anything else interesting in the article about the Beatles' cultural impact with psychedelia and progressive music besides defining progressiveness, defining psychedelia, contributing to progressiveness, creating a musical craze for the Sitar, and beginning to use droning guitars?
Sgt. Pepper's Lonely Hearts Club Band is viewed as originating the progressive rock genre due to the album's lyrical unity, extended structure, complexity, eclecticism, experimentalism and derivative classical music forms

Question: When was Sgt. Pepper's released?
Self-contained rewrite: When was Sgt. Pepper's Lonely Hearts Club Band released?