Samba is the most popular form of music in Brasil.  Many singers and percussionists study at the many samba schools currently functioning in Brasil, banding together to form the ensembles which play during the Carnaval in Rio, and during other holidays.  

During the late 1950's samba mutated into Bossa Nova, when Joao Gilberto recreated on his guitar a sound which previously required a huge percussion ensemble.  He and the late Antonio Carlos Jobim, along with several others, became the voices of a disenfranchised young generation in Brasil, a generation for whom previously the only form of music heard on the radio had been tango ballads.  

Bossa Nova's first noticeable appearance in the US was on Stan Getz' version of Jobim's Desafinado.  The song was a huge success, and within weeks practically every jazz artist, singer, and bandleader was releasing a Bossa Nova album.

One day, as Jobim and his lyricist Viniu Morales? sat in a bar they noticed, and not for the first time, a beautiful young woman who walked each day to the beach near the elite section of Rio to exercise.  They began to discuss how she never looked at anyone, she merely kept her eyes straight ahead as she walked to the beach from her native Ipanema, and a song which was to become the anthem of the Bossa Nova movement (in the United States, at least) was born.

For me, the era of  Bossa Nova came to an abrupt end with the passing of Jobim.  After recording Fly Me To The Moon with Sinatra for the second Duets album, he checked into Mount Sinai Hospital in New York for some routine tests.  He never left.  At his funeral in Rio the open hearse carrying his casket passed by the beach at Ipanema, then stopped.  A beautiful woman in black walked up to the hearse and placed a single red rose on the casket.  The crowd, silent recognised her and began to sing the song written for her decades ago.  The Girl From Ipanema, now a TV commentator and a star in her own right, had said her final farewell to Rio's master musician.

For further research I highly recommend the collections Samba, Bossa Nova, 30 Anos Depois on Verve, plus David Byrne's exhaustively researched collections of Brasilian Music on the Sire label.  

What is left of Orson Welles' Brasilian doccumentary from the early 40's, It's All True, is also quite illuminating.

Finally I would recommend the albums Txai and Anima by Milton Nascimento (Samba and beyond), Amoroso/Brasil (two albums on one CD) and The Legendary Joao Gilberto by Joao Gilberto, and The Composer Plays and Wave by Antonio Carlos Jobim.