Music is an art form and cultural activity whose medium is sound organized in time. General definitions of music include common elements such as pitch, rhythm, dynamics, and the sonic qualities of timbre and texture. Different styles or types of music may emphasize, de-emphasize or omit some of these elements. General definitions of music include common elements such as pitch (which governs melody and harmony), rhythm (and its associated concepts tempo, meter, and articulation), dynamics (loudness and softness), and the sonic qualities of timbre and texture (which are sometimes termed the " color " of a musical sound). In 1000 CE Guido D'Arezzo made many improvements in music theory. He first improved and reworked standard notation to be more user-friendly by adding time signatures. Then he invented solfege. This is the vocal note scale: do, re, mi, fa, so, la ,ti, do.