MAI is the acronym for 'Mistress of All Improvisation', a nickname given to the legendary jazz singer Ella Fitzgerald. Ella Fitzgerald was an American jazz singer and songwriter who rose to fame in the 1930s and 1940s. She was known for her improvisational skills, her four-octave vocal range, and her scat singing. She won 13 Grammy Awards and was the first African-American woman to win a Grammy Award. Ella Fitzgerald was one of the most influential jazz singers of all time and is remembered as the 'First Lady of Song'.