The style of realism is just that point blank, real. What the artist sees in their eyes, there is no interpretation or adding of anything. It is the capturing of people or objects as they really are with no flourishing. The attempt of the artist is usually to capture what the subject or object in a very real, direct way. No abstraction and imagination just figures and objects doing normal everyday things that they do even if it was a rather grim or ugly picture.
This is in opposition to idealism which tends to create a scenario of what life and situations should be like in an idealistic world. Idealism added what the artist or imagination thought the world could be like with some improvements and embellishments. Realism is the total opposite and sometimes does not paint a pretty picture of the world but rather a real sometimes ugly portrayal of life where only truth of exactly what the eyes see is portrayed quite often commonplace subjects.
During the mid 1800?s realism grew in popularity, not just in painting style but in literature as well. There are strong ties to political reform throughout the time period and can be linked with the social atmosphere of the times. Ususally with realism there is a moral or social message in some of realism depictions of life. It was art of the common people in a straight forward depiction of their lives, so to speak
Realism actually came about long before the 1800?s as far back as 2400 BC in a broad sense and started once again in the early 19th century but the era really did not come into play as an art movement until the mid 19th century. Artists then became somewhat disillusioned with the more romanticized depictions of life that had been portrayed before hand. Formally the realism art movement is credited to have emerged in the country of France during the 1848 Revolution.
Gustave Courbet in 1855 rather scandalized the world with his exhibits, his art was thought to be somewhat shocking with its blatant truthfulness. Until then the world had been exposed to art that was steeped in Romanticism or the ideals of the Old Masters.
Rembrandt is one of the most famous realism artists. Craftsmanship and staying true to colors is a trademark of realism. Technical skill is adhered to because the paintings subject must be easily recognizable. It must stay as true to life as possible even if the subject matter is far less then pretty.
Realism is still very much alive in our modern times. Cinema, television, photography are all examples of realism. There have always been the art forms that show the world in a divine and imaginative way of how things should be. There have also been those that strived to keep art as a true depiction of life. In today?s world you will still find both but basically we have come to a balance of the two worlds.