Let personal taste guide all decisions. A well-rounded classic rock collection, however, should at least include a few albums by certain hugely influential artists.
Begin by buying some Beatles. The Beatles are widely recognized as one of the most commercially and critically successful rock and roll groups of all time. From 1965 to 1969, they released a string of studio albums that redefined the possibilities of popular music. "Rubber Soul" (1965), "Revolver" (1966), "Sergeant Pepper's Lonely Heart's Club Band" (1967) and "Abbey Road" (1969) contain some of the most famous music of the generation and form an ideal cornerstone to any record collection.
Listen to Bob Dylan. Just as the Beatles revolutionized sonic possibilities, Bob Dylan revolutionized lyrical possibilities. He used folk and blues music as a means of writing topical songs critiquing popular culture and society. Much of his best work can be found on "Bringing It All Back Home" (1965), "Highway 61 Revisited" (1965), "Blonde on Blonde" (1966) and "Blood on the Tracks" (1975).
Complete the foundation of your collection by buying a Jimi Hendrix record. Jimi Hendrix was perhaps the most innovative guitarist of all time, and one of the first musicians to fully explore the artistic possibilities of distortion and feedback. No record collection is complete without his masterpiece "Are You Experienced?" (1967).
Look at the four broad categories of classic rock and roll, although be aware that such classifications are hardly official.
Explore blues rock. Blues rock is a form of classic rock which applies rock-and-roll sounds (like distorted guitars and loud drums) to American blues forms, which derive from southern slave spirituals. To get a feel for blues rock, listen to these albums: "Led Zeppelin II" by Led Zeppelin (1969), "Disraeli Gears" by Cream (1967) and "Exile on Main Street" by the Rolling Stones (1972).
Listen to various folk rock artists. Folk rock uses acoustic guitars and vocal harmonies to create a more mellow sound. Famous folk rock albums include "Déjà Vu" by Crosby, Stills, Nash & Young (1970), "Rumours" by Fleetwood Mac (1977) and "Jackson Browne" by Jackson Browne (1972).
Pick up a few progressive rock albums if you're feeling adventurous. Progressive rock, or "prog rock," features longer songs, unconventional, challenging musical structures and often abstract lyrics. The most well-known prog rock albums are Pink Floyd's "The Dark Side of the Moon" (1973) and "Wish You Were Here" (1975). Other good starting points are "The Yes Album" by Yes (1972) and "The Low Spark of High-Heeled Boys" by Traffic (1971).
Check out some glam rock tunes. Glam rock was a largely British genre that focused on live theatrics, often including costumes, and catchy, distortion-heavy tunes. Start with "The Rise and Fall of Ziggy Stardust and the Spiders From Mars" by David Bowie (1972) and "All the Young Dudes" by Mott the Hoople (1972).
Remember that these categories are only suggestions. Hundreds of other bands made innovative, important and enjoyable music during the classic rock era. Many such groups, like the Doors and the Who, don't fit neatly into any genre description. This guide should be used as a starting point, from which the enthusiastic listener can begin on a lifelong appreciation of rock and roll.