The Renaissance was an intense period of innovation, change and  development that began in the 14th century and continued until the 17th  century. Its influence affected literature, philosophy, art, politics,  science and religion, but also extended beyond these areas into many  other aspects of intellectual inquiry.
It is generally believed to have begun in Florence, Italy, in the Late  Middle Ages and later spread across the rest of Europe. In part it was a  consequence of a renewed interest by the scholars of the time in ancient  Latin and Greek literature and history, where before they had focused  principally on works of natural science, philosophy and mathematics.
David by Michelangelo, 1504
Vitruvian Man by Leonardo, 1485
Detail from the Sistine Chapel by Michelangelo, 1508
Mona Lisa by Leonardo, 1505
But to really understand and appreciate the significance of the  Renaissance, in terms of it's influence on Art and Design, it is  necessary to look at the kind of artworks that were being made before  it. Compare an image made prior to the Renaissance, during what is known  as the Medieval period, to one made during it:
Giotto di Bondone, 1310, Tempera on wood
Leonardo da Vinci, 1505, Oil on wood
One way to begin to understand the significance of the Renaissance is to   look at the similarities and differences between these two images. 
  Starting with the similarities, both are of a religious subject, the   Virgin mother and child. In each these figures provide the principal   focal point, with the other imagery framing them or comprising the   background. It is here that we begin to notice some obvious differences   between the images. In the first image the background and the figures  in  the foreground are both pushed up towards what is known as the  picture  plane, or the surface of the picture. There is a suggestion of  depth,  but it feels relatively forced and inaccurate. Likewise, the  modeling on  the figures feels a bit flat and awkward as though the  artist is trying  to suggest three dimentions but doesn't quite know how  to do it. By  comparison the second image is much more successfully  three  dimentionally modeled. As can be seen from the detail below, the  figures  have a much more successful sense of form, which no longer  feels forced  or awkward, even where the drawing is still in  parts  inaccurate. 
Although the background to the image still  looks somewhat  flat, as though it were a theatrical backdrop, it is  rendered with far  greater detail and the suggestion of depth is much  more effective than in the earlier example. 
Detail
Here are some more examples of art works from the Medieval period, see if you can identify ways in which they are different from the Renaissance images which follow: 
 fig.1
 fig.2
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fig.6
 fig.7
 fig.8
Ancient Greek and Roman art works:
 Laocoon, 1st Century BC
Hermes and Dionysos, 4th Century BC
 Discus thrower, 4th Century BC



 
 















