Andy Warhol is a very well-known artist for pop art which became very popular in the late 20th century. Though he is mostly remembered for his paintings, he had also created other works such as commercial advertisements and films.
Around the 1960, Andy Warhol had decided to make a name for him in pop art. Back then, pop art was a new style of art. It began in the mid-1950s in England. Pop art consists of realistic interpretations of popular everyday items.
Warhol was used to a blotted-line technique which is a technique where one has to tape two pieces of blank paper together and then draws in ink on one page. Then both the pages would be pressed together. The result would be a picture with irregular lines in which Andy Warhol would colour in with watercolours. Therefore when he tried pop art, it was a bit difficult for him to use paint and canvas and had some trouble deciding what to paint.

In 1962 Warhol’s first exhibition was up at the Ferus Gallery in Los Angeles. His canvases of Campbell’s soup were displayed, one canvas for each of the 32 types of Campbell’s soup. Lastly, he sold all the paintings as a set for a $1000.
By experience, Warhol noticed that he couldn’t make his paintings fast enough on canvas. In 1962, the artist discovered the process of silk screening. Silk screening is a technique which uses a specially prepared section of silk as a stencil, allowing one silk screen to create similar patterns for a lot of times. He immediately began making paintings of celebrities. His most common one is the large collection of Marilyn Monroe. Warhol would have used this style for the rest of his life.
References:
About, 2014. 20th Century History. [online] Available at: <http://history1900s.about.com/od/artists/p/warhol.htm> [Accessed 26, February 2014]