Back in the 18th century, when piano music was popular and creative, composers needed to develop new patterns and ways to convey music in order to captivate audiences. As the Baroque period transitioned into the Classical era, the style of music changed in a way that reflected social norms and events occurring at the time. While still utilizing the musical devices such as the contrapuntalism of the earlier eras, Classical music become much simpler and lighter. To appeal to the public with this simple music, the Alberti bass was largely utilized, especially among keyboard music pieces during the Classical era. Although it was not developed by Domenico Alberti himself, it was named after him because he was the first to extensively use the device. Mozart too was a notable user of the Alberti Bass.
The Alberti Bass is an accompaniment that is often played by the left hand on a keyboard or lower instruments in an ensemble. The accompaniment consists of a broken chord pattern, where the 3 notes of a triad or inversion (1st, 3rd, and 5th), are played in the order 1, 5, 3, 5 (or 1, 5, 3, 5, 3, 5 in triple meter time signatures). The pattern itself not only allowed for a new form of music but also created a smooth and sustained accompaniment that sounded nice on a wide variety of instruments.
The Alberti bass as can be seen in the left hand (bass clef) http://www.music.vt.edu/MUSICDICTIONARY/texta/AlbertiBass.html
musematics 
