Aria is a type of song with instrumental accompaniment usually performed by a solo singer in an opera or oratorio. Some arias are written for two or more singers. Arias mark points of heightened feelings and expression within the dramatic action of an opera. They also mark moments of thoughtful reflection. From opera's beginnings in the late 1500's and early 1600's, composers needed to make a distinction within a dramatic musical work between the process of carrying the plot forward and stopping for a moment of emotion or contemplation. They used recitative (recited singing) or spoken dialogue to develop the plot and developed the aria for emotional or contemplative moments.