Music historians divide the European classical music repertory into various eras based on what style was most popular as taste changed. These eras and styles include Medieval, Renaissance,   Baroque, Classical, Romantic, and 20th century. Some of the terms, such as "Renaissance" and "Baroque", are borrowed from Western art history. Approximate dates can be assigned to the beginning and ending of each of these eras, which can be useful in describing changes in taste and to estimate the style of a work composed in a particular year. However, these dates are approximate and even good approximations are hard to make.