Maria Callas (Greek: Μαρία Κάλλας) (December 2, 1923 – September 16, 1977) was an American-born Greek soprano and one of the most renowned opera singers of the 20th century. She combined an impressive bel canto technique, a wide-ranging voice, and great dramatic gifts. An extremely versatile singer, her repertoire ranged from classical opera seria to the bel canto operas of Donizetti, Bellini and Rossini; further, to the works of Verdi and Puccini; and, in her early career, to the music dramas of Wagner. Her remarkable musical and dramatic talents led to her being hailed as La Divina.

Born in New York City and raised by an overbearing mother, she received her musical education in Greece and established her career in Italy. Forced to deal with the exigencies of wartime poverty and with myopia that left her nearly blind on stage, she endured struggles and scandal over the course of her career. She turned herself from a heavy woman into a svelte and glamorous one after a mid-career weight loss, which might have contributed to her vocal decline and the premature end of her career. The press exulted in publicizing Callas's allegedly temperamental behavior, her supposed rivalry with Renata Tebaldi, and her love affair with Aristotle Onassis. Her dramatic life and personal tragedy have often overshadowed Callas the artist in the popular press. However, her artistic achievements were such that Leonard Bernstein called her "The Bible of opera", and her influence so enduring that, in 2006, Opera News wrote of her: "Nearly thirty years after her death, she's still the definition of the diva as artist—and still one of classical music's best-selling vocalists."

Data from the Internet, Text from Wikipedia

The Bel Canto technique

Bel canto means, most literally, "beautiful singing." It is a term used to describe all Italian singing, but in particular the light, bright quality that Italian opera singers use to charm audiences. Despite bel canto's popularity, it is shrouded in obscurity. The history of this art is a complicated and mysterious one.

Bel canto emerged in the sixteenth and seventeenth centuries, but its roots lie all the way through the Middle Ages. It began in the singing instruction that Italian masters provided their students. Because singing must be mastered internally, teaching singing is tricky. Italian masters relied on a system of teaching and listening to their pupils. When the pupil created a tone or sound that was of admirable quality, the master would urge that pupil to repeat the sound until it was ingrained in their memory. This practice became so inherent to Italian singers that Italian singing became shrouded in mystery. Many thought that Italy was protecting its singing mastery from foreign countries, when in reality it was simply espousing a valuable teaching style.
 
Bel canto was initially used by men, and, at its earliest, by male religious singers. The Italian castrati were famous for their use of this singing style. During the time of the Renaissance, the period when opera was created in Italy, bel canto became the singing style used for this new art form. Later, it became famous through use by other operatic singers, notably sopranos. Today, it is sopranos like Joan Sutherland and Kathleen Battle that keep this tradition alive.

The secret to bel canto, some claim, lays in continuity of tone. Many singers are judged on their ability to pass from one musical phrase to the next with little to no interruption. The art of sustaining passages to create a beautiful line can be seen in the performances of the most famous bel canto singers.

Italian singing itself is very dependent upon the Italian language. Italian words often contain consonants strung together with vowel sounds. Because of this, their language is very fluid and, when spoken correctly, it resonates in the facial structure. Italian singers make full use of these vowels, because they allow long, continuous lines in singing. Italian singing contains little distinction between the start of tone and the intake of breath. This, too, contributes to a continuous line. Finally, Italians consider singing to be a natural act instead of an unnatural one. Therefore, true Italian singing, and true bel canto singing, is an extension of normal speaking and voice expression.

Rossini, Donizetti, Bellini, Marcello and Pacini are some of the most famous bel canto composers. In their operas, one finds the light, soaring soprano and tenor arias that have made Italian opera famous. While many consider bel canto to be an art that has "died," bel canto is, by its very nature, Italian singing. Therefore, it will exist as long as Italian singing does. From the popularity of Andrea Bocelli and other Italian singing stars, one can see that bel canto will be around for quite a long time.