A melodic line is the succession of notes that constitute a melody. It, and or variations of it, is typically repeated multiple times. And into it are often inserted extra notes, such as grace notes and trills, by the composer or the performer to add complexity and interest.
Basic characteristics of a melodic line include its contour and range. Contour is the overall direction of and speed of change in pitch, including whether it is ascending, descending, gradual, stepwise, or leaping, while range is the distance between the lowest and highest note.
Music containing a single melodic line is termed monophony and music containing multiple simultaneous melodic lines is called polyphony. A brief melodic line is sometimes called a musical phrase, a motif, or a riff.