Formed in New Jersey, USA. In 1960, the group known as The Four Lovers evolved into The Four Seasons, with Frankie Valli as the lead singer, Bob Gaudio (formerly of The Royal Teens) on keyboards and tenor vocals, Tommy DeVito on lead guitar and baritone vocals and Nick Massi on bass guitar and bass vocals (Massi was replaced in 1965 by Charles Calello, who was in turn replaced later in 1965 by Joe Long on bass guitar and bass vocals).
While singers, producers, and musicians have come and gone, Gaudio and Valli remain the group's constant.
The Four Seasons released their first single in 1961 ("Bermuda"/"Spanish Lace" on Gone Records). While the single did not chart, the songs gave the group enough of a following to be signed with Vee Jay Records late that year.
In 1962, the group released their first album featuring the single "Sherry", which was not only their first charted hit but also their first number one song. Under the guidance of producer/songwriter Bob Crewe, The Four Seasons followed up "Sherry" with several million-selling hits, including "Big Girls Don't Cry" (their second #1 hit), "Walk Like a Man" (their third #1), "Candy Girl", "Ain't That a Shame", and several others. In addition, they released a Christmas album in December of 1962 and charted with a unique rendition of "Santa Claus Is Coming to Town".
From 1962 to early 1964, only the Beach Boys matched the Four Seasons in record sales in the United States, and their first three Vee Jay non-holiday single releases marked the first time that a vocal group hit #1 on the Billboard singles charts with three consecutive entries (ignoring their version of "Santa Claus Is Coming to Town").
At the end of 1963 The Four Seasons left Vee Jay Records and moved over to Philips Records. In the settlement of the lawsuit against Vee Jay in 1965, Vee Jay retained release rights for all material the group recorded for the label and exercised them liberally over the following three years. The group was obligated to deliver one final album to Vee Jay, which they did in the form of a live LP.
The change of label did not diminish the popularity of the Four Seasons in 1964, nor did the onslaught of the British Invasion and Beatlemania. However, "Dawn (Go Away)" was kept from the #1 spot on the Hot 100 by no fewer than three Beatles singles in the March 21, 1964, edition (two weeks later, the top 5 slots were filled by Beatles singles).
In mid-July of that year, the Four Seasons made their fourth trip to the top of the singles charts with "Rag Doll"; additional massive-selling singles from 1964 on their new label included "Ronnie", "Big Man in Town", "Save It For Me", "Bye, Bye, Baby (Baby Goodbye)", and "Girl Come Running". In the meantime, Vee Jay continued releasing Four Seasons singles from their vault, including "Stay" and "Alone."
More Top 20 singles credited to the Four Seasons followed in 1965, 1966, and 1967, including "Let's Hang On!", "Don't Think Twice", "Working My Way Back to You", "Opus 17 (Don't You Worry 'Bout Me)", "I've Got You Under My Skin", "Beggin'", "Tell It to the Rain" and "C'mon Marianne" . By late 1967, like that of their West Coast brethren, The Beach Boys, the Four Seasons' record sales were tapering off. "Will You Love Me Tomorrow" provided a "last hurrah" for the group in early 1968 (reaching #24 on the Hot 100).
By 1969 the group's popularity was deteriorating as public interest moved away from street corner pop and towards rock with a harder edge, deeper soul music, and music with more socially conscious lyrics. The group's last single on Philips, "Patch of Blue," featured the group's name as "Frankie Valli & the Four Seasons," but the change in billing did not change the act's lack of success in 1970.
Various incarnations of the group have toured and recorded up till this day.
source: wikipedia and record booklets