Characteristics of Impressionist paintings include relatively small, thin, yet visible brush strokes, open composition, emphasis on the accurate depiction of light in its changing qualities (often accentuating the effects of the passage of time), ordinary subject matter, the inclusion of movement as a crucial element of human perception and experience, and unusual visual angles. The emergence of Impressionism in the visual arts was soon followed by analogous movements in other media which became known as Impressionist music and Impressionist literature.

Impressionism also describes art created in this style, but outside of the late 19th century time period.

Radicals in their time, early Impressionists broke the rules of academic painting. They began by giving colours, freely brushed, primacy over line, drawing inspiration from the work of painters such as Eugène Delacroix. They also took the act of painting out of the studio and into the modern world. Previously, still lifes and portraits as well as landscapes had usually been painted indoors. The Impressionists found that they could capture the momentary and transient effects of sunlight by painting en plein air. Painting realistic scenes of modern life, they portrayed overall visual effects instead of details. They used short "broken" brush strokes of mixed and pure unmixed colour, not smoothly blended or shaded, as was customary, in order to achieve the effect of intense colour vibration.

Although the rise of Impressionism in France happened at a time when a number of other painters, including the Italian artists known as the Macchiaioli, and Winslow Homer in the United States, were also exploring plein-air painting, the Impressionists developed new techniques that were specific to the movement. Encompassing what its adherents argued was a different way of seeing, it was an art of immediacy and movement, of candid poses and compositions, of the play of light expressed in a bright and varied use of colour.

The public, at first hostile, gradually came to believe that the Impressionists had captured a fresh and original vision, even if it did not receive the approval of the art critics and establishment.

By re-creating the sensation in the eye that views the subject, rather than recreating the subject, and by creating a welter of techniques and forms, Impressionism became a precursor seminal to various movements in painting which would follow, including Neo-Impressionism, Post-Impressionism, Fauvism, and Cubism.

In an atmosphere of change as Emperor Napoleon III rebuilt Paris and waged war, the Académie des Beaux-Arts dominated the French art scene in the middle of the 19th century. The Académie was the upholder of traditional standards for French painting, both in content and style. Historical subjects, religious themes, and portraits were valued (landscape and still life were not), and the Académie preferred carefully finished images which mirrored reality when examined closely. Colour was somber and conservative, and the traces of brush strokes were suppressed, concealing the artist's personality, emotions, and working techniques.

The Académie held an annual, juried art show, the Salon de Paris, and artists whose work displayed in the show won prizes, garnered commissions, and enhanced their prestige. The standards of the juries reflected the values of the Académie, represented by the highly polished works of such artists as Jean-Léon Gérôme and Alexandre Cabanel. Some younger artists painted in a lighter and brighter manner than painters of the preceding generation, extending further the realism of Gustave Courbet and the Barbizon school. They were more interested in painting landscape and contemporary life than in recreating scenes from history. Each year, they submitted their art to the Salon, only to see the juries reject their best efforts in favour of trivial works by artists working in the approved style. A core group of young realists, Claude Monet, Pierre-Auguste Renoir, Alfred Sisley, and Frédéric Bazille, who had studied under Charles Gleyre, became friends and often painted together. They soon were joined by Camille Pissarro, Paul Cézanne, and Armand Guillaumin.

In 1863, the jury rejected The Luncheon on the Grass (Le déjeuner sur l'herbe) by Édouard Manet primarily because it depicted a nude woman with two clothed men at a picnic. While nudes were routinely accepted by the Salon when featured in historical and allegorical paintings, the jury condemned Manet for placing a realistic nude in a contemporary setting. The jury's sharply worded rejection of Manet's painting, as well as the unusually large number of rejected works that year, set off a firestorm among French artists. Manet was admired by Monet and his friends, and led the discussions at Café Guerbois where the group of artists frequently met.

After seeing the rejected works in 1863, Emperor Napoleon III decreed that the public be allowed to judge the work themselves, and the Salon des Refusés (Salon of the Refused) was organized. While many viewers came only to laugh, the Salon des Refusés drew attention to the existence of a new tendency in art and attracted more visitors than the regular Salon.