Music has not always be written the same way. As stated at Gabriella Scelta's Music Symbol site, by the 1700s, the use of a five line staff to write music was firmly established. According to Exploring The Arts Foundation, the use of a 4 line staff appeared in the 10th century and a system of fixed note lengths arose in the 14th century. "Vertical bar lines that divide the staff into sections appeared in the 15th century. By the early 16th century, notation had assumed much of its modern form, with the essential components of staff, clef, Time signature and durational values, though bar lines only gradually became widespread during the 16th and 17th centuries as an aid in ensemble performance. Regular measures (bars) became commonplace by the end of the 17th century." Music today is still evolving and practices used in Western Music have been adopted by all musicians worldwide. Modern music evolved from plainsong notation.