The Beatles are among the most influential popular music artists of the second half of the 20th century, affecting the culture of Britain and America and the postwar baby boom generation, and the entire English-speaking world, especially during the 1960s and early 1970s. They synthesized all that was good about early rock and roll, and changed it into something original and even more exciting. They established the prototype for the self-contained rock group that wrote and performed their own material. As composers, their craft, melodic inventiveness, and lyrics were second to none, and key to the evolution of rock from its blues/R&B-based forms into a style that was far more eclectic, but equally visceral. As singers, both John Lennon and Paul McCartney were among the best and most expressive vocalists in rock; the group's harmonies were intricate and exhilarating. As performers, they were (at least until touring had ground them down) exciting and photogenic; when they retreated into the studio, they were instrumental in pioneering advanced techniques and multi-layered arrangements. The Beatles were also the first British rock group to achieve worldwide prominence, launching a British Invasion that made rock truly an international phenomenon...