Cubism paintings

Writing woman

Cubism originated in the first decade of the twentieth century. It is an abstract art form where the normally observed view is dissected by the artist and then put back together again, but with the conventions of representational art removed. Complex shapes are reduced to basic geometries, depth cues are removed, and faces which would not be visible to the observer from one position are nonetheless represented on the canvas. It is definitely one of the more academic art forms and the first branch of Cubism, Analytic Cubism, was well named.
To understand Picasso and Cubism it is important to know something about both the artist's development and the state of art at the time.
The Evolution of Cubism
Pablo Picasso and Georges Braque are credited with the invention of Cubism. Accounts differ as to whether it originally Braque's or Picasso's idea or whether it was a genuinely equal discovery. The most widely accepted version is that Picasso persuaded Braque to make the move from Fauvism to the new form.

The red horseman

Cubism did not spring from nothing though, and its roots can certainly be seen in the work of the Post Impressionists Gauguin and Cezanne, especially the latter. Cezanne was a reductionist; he stated that all of nature could be reduced to simple geometric forms such as spheres, cylinders, and cones. More importantly, he developed a style that used what can best be described as facets of color which gave his paintings a sense of more than one viewpoint. There is general agreement, however, that these works were not truly Cubist. The first true Cubist works from Picasso and Braque did not just use viewpoints that were relatively close in space, like Cezanne, but would go to the extreme of showing both the back and the front of an object next to each other and on the same canvas.
Picasso's Formal Art Training 
Picasso received formal art training from his father, starting at age seven. By age thirteen his father, a respected art academic, announced that his son had surpassed him and gave up painting. Picasso attended formal art schools but he didn't respond well to them, possibly due to finding the work too easy, and his father was his main teaching influence. Many people assume that Picasso only worked with abstraction but this is far from the truth. His father was a hard taskmaster and emphasized the importance of copying the work of the Masters and of studying the human figure.
Blue and Rose Periods
Picasso's working life is often broken up into artistic periods. Paintings from his Blue Period were generally pessimistic in nature and the predominant color was blue. Next came the Rose period when his paintings became warmer in tone and more optimistic. Both of these periods were characterized by being representational with little hint to the level of abstraction that was going to become the hallmark of Picasso's works. He did gradually increase his use of symbolism during these periods and this provides a less tenuous connection to his later work.
African Period

Lovers in pink

After the Rose Period came his African or African Influenced period. The paintings from this time show a definite trend towards the Cubism which would come later. The paintings from this period possess the use of geometry and composition, as well as the palette which would carry over into Cubism, but the underpinning philosophy of the art form had yet to take shape. Analytical Cubism introduced a level of detachment and a movement away from the expressive which was a prerequisite of modern art, especially minimalism and conceptual art. Undoubtedly it was Picasso's friendship and conversations with Braque that facilitated the jump from the largely decorative African Period to the much more substantive Cubism.
Picasso and Cubism
Picasso produced Cubist work for a decade from 1909 until just after World War I. The first three years were spent developing Analytical Cubism and the next seven, Synthetic Cubism. Synthetic Cubism was developed by Picasso and Braque along with Juan Gris. A strong argument can be made that Gris was actually the pioneer of Synthetic Cubism and Braque and Picasso the followers. Unlike the inventors of Analytical Cubism Gris tended to work with strong bright colors and often used them in unconventional ways.
Further Reading

Two Figures paintin

No artist or art period can be studied in isolation from either their geography or their time. To understand both Picasso and Cubism, it is essential to know a little about the other artists working at the time and about the artists who in turn influenced them. With this in mind I'd recommend gaining an overview of Picasso, and of the following artists at the very least.

• Matisse
• Cezanne
• Gauguin
• Braque
• Gris

Wikipedia is an excellent resource and it is always enlightening to read not only the main page for each subject but also the discussion pages. Art history is no different than any other history in as much as different interpretations are always possible and the Wikipedia discussion pages give a good insight into this process.