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 eugene 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 emphasized vivid overall effects rather than details. They used short, "broken" brush strokes of pure and unmixed colour, not smoothly blended, 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 Academie des Beaux-Arts dominated the French art scene in the middle of the 19th century. The Academie 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 Academie 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 Academie 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 Academie, represented by the highly polished works of such artists as Jean-Leon Gerôme 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 Frederic Bazille, who had studied under Charles Gleyre, became friends and often painted together. They soon were joined by Camille Pissarro, Paul Cezanne, and Armand Guillaumin.

In 1863, the jury rejected The Luncheon on the Grass (Le dejeuner sur l'herbe) by Edouard 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 Cafe 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 Refuses (Salon of the Refused) was organized. While many viewers came only to laugh, the Salon des Refuses drew attention to the existence of a new tendency in art and attracted more visitors than the regular Salon.

Artists' petitions requesting a new Salon des Refuses in 1867, and again in 1872, were denied. In the latter part of 1873, Monet, Renoir, Pissarro, and Sisley organized the Societe Anonyme Cooperative des Artistes Peintres, Sculpteurs, Graveurs ("Cooperative and Anonymous Association of Painters, Sculptors, and engravers") for the purpose of exhibiting their artworks independently. Members of the association, which soon included Cezanne, Berthe Morisot, and Edgar Degas, were expected to forswear participation in the Salon. The organizers invited a number of other progressive artists to join them in their inaugural exhibition, including the slightly older eugene Boudin, whose example had first persuaded Monet to take up plein air painting years before. Another painter who greatly influenced Monet and his friends, Johan Jongkind, declined to participate, as did Manet. In total, thirty artists participated in their first exhibition, held in April 1874 at the studio of the photographer Nadar. Claude Monet, The Cliff at etretat after the Storm, 1885, Clark Art Institute, Williamstown, Massachusetts

The critical response was mixed, with Monet and Cezanne bearing the harshest attacks. Critic and humorist Louis Leroy wrote a scathing review in the Le Charivari newspaper in which, making wordplay with the title of Claude Monet's Impression, Sunrise (Impression, soleil levant), he gave the artists the name by which they would become known. Derisively titling his article The exhibition of the Impressionists, Leroy declared that Monet's painting was at most, a sketch, and could hardly be termed a finished work.

He wrote, in the form of a dialog between viewers,

Impression - I was certain of it. I was just telling myself that, since I was impressed, there had to be some impression in it ... and what freedom, what ease of workmanship! Wallpaper in its embryonic state is more finished than that seascape.

The term "Impressionists" quickly gained favour with the public. It was also accepted by the artists themselves, even though they were a diverse group in style and temperament, unified primarily by their spirit of independence and rebellion. They exhibited together-albeit with shifting membership-eight times between 1874 and 1886.

Monet, Sisley, Morisot, and Pissarro may be considered the "purest" Impressionists, in their consistent pursuit of an art of spontaneity, sunlight, and colour. Degas rejected much of this, as he believed in the primacy of drawing over colour and belittled the practice of painting outdoors. Renoir turned against Impressionism for a time in the 1880s, and never entirely regained his commitment to its ideas. Edouard Manet, despite his role as a leader to the group, never abandoned his liberal use of black as a colour, and never participated in the Impressionist exhibitions. He continued to submit his works to the Salon, where his Spanish Singer had won a 2nd class medal in 1861, and he urged the others to do likewise, arguing that "the Salon is the real field of battle" where a reputation could be made.

Among the artists of the core group (minus Bazille, who had died in the Franco-Prussian War in 1870), defections occurred as Cezanne, followed later by Renoir, Sisley, and Monet, abstained from the group exhibitions in order to submit their works to the Salon. Disagreements arose from issues such as Guillaumin's membership in the group, championed by Pissarro and Cezanne against opposition from Monet and Degas, who thought him unworthy. Degas invited Mary Cassatt to display her work in the 1879 exhibition, but he also caused dissention by insisting on the inclusion of Jean-Francois Raffaelli, Ludovic Lepic, and other realists who did not represent Impressionist practices, leading Monet in 1880 to accuse the Impressionists of "opening doors to first-come daubers". The group divided over the invitation of Signac and Seurat to exhibit with them in 1886. Pissarro was the only artist to show at all eight Impressionist exhibitions.

The individual artists saw few financial rewards from the Impressionist exhibitions, but their art gradually won a degree of public acceptance. Their dealer, Durand-Ruel, played a major role in this as he kept their work before the public and arranged shows for them in London and New York. Although Sisley would die in poverty in 1899, Renoir had a great Salon success in 1879. Financial security came to Monet in the early 1880s and to Pissarro by the early 1890s. By this time the methods of Impressionist painting, in a diluted form, had become commonplace in Salon art.

Painters throughout history had occasionally used these methods, but Impressionists were the first to use all of them together, and with such boldness. earlier artists whose works display these techniques include Frans Hals, Diego Velázquez, Peter Paul Rubens, John Constable, and J. M. W. Turner.

Prior to the Impressionists, other painters, notably such 17th-century Dutch painters as Jan Steen, had focused on common subjects, but their approaches to composition were traditional. They arranged their compositions in such a way that the main subject commanded the viewer's attention. The Impressionists relaxed the boundary between subject and background so that the effect of an Impressionist painting often resembles a snapshot, a part of a larger reality captured as if by chance. Photography was gaining popularity, and as cameras became more portable, photographs became more candid. Photography inspired Impressionists to capture the moment, not only in the fleeting lights of a landscape, but in the day-to-day lives of people.

The rise of the impressionist movement can be seen in part as a reaction by artists to the newly established medium of photography. The taking of fixed or still images challenged painters by providing a new medium with which to capture reality. Initially photography's presence seemed to undermine the artist's depiction of nature and their ability to mirror reality. Both portrait and landscape paintings were deemed somewhat deficient and lacking in truth as photography "produced lifelike images much more efficiently and reliably". Alfred Sisley, View of the Saint-Martin Canal, Paris, 1870, Musee d'Orsay

In spite of this, photography actually inspired artists to pursue other means of artistic expression, and rather than competing with photography to emulate reality, artists focused "on the one thing they could inevitably do better than the photograph – by further developing into an art form its very subjectivity in the conception of the image, the very subjectivity that photography eliminated". The Impressionists sought to express their perceptions of nature, rather than create exacting reflections or mirror images of the world. This allowed artists to subjectively depict what they saw with their "tacit imperatives of taste and conscience". Photography encouraged painters to exploit aspects of the painting medium, like colour, which photography then lacked; "the Impressionists were the first to consciously offer a subjective alternative to the photograph".

Another major influence was Japanese art prints (Japonism), which had originally come into France as wrapping paper for imported goods. The art of these prints contributed significantly to the "snapshot" angles and unconventional compositions which would become characteristic of the movement.

Edgar Degas was both an avid photographer and a collector of Japanese prints. His The Dance Class (La classe de danse) of 1874 shows both influences in its asymmetrical composition. The dancers are seemingly caught off guard in various awkward poses, leaving an expanse of empty floor space in the lower right quadrant.

The central figures in the development of Impressionism in France, listed alphabetically, were: