From Wikipedia: Charles Baudelaire, (April 9, 1821 – August 31, 1867) was a French poet who also produced notable work as an essayist, art critic, and pioneering translator of Edgar Allan Poe. Baudelaire was one of the major innovators in French literature. His poetry is influenced by the French romantic poets of the earlier 19th century, although its attention to the formal features of verse connect it more closely to the work of the contemporary 'Parnassians'. As for theme and tone, in his works we see the rejection of the belief in the supremacy of nature and the fundamental goodness of man as typically espoused by the romantics and expressed by them in rhetorical, effusive and public voice in favor of a new urban sensibility, an awareness of individual moral complexity, an interest in vice (linked with decadence) and refined sensual and aesthetical pleasures, and the use of urban subject matter, such as the city, the crowd, individual passers-by, all expressed in highly ordered verse, sometimes through a cynical and ironic voice. Formally, the use of sound to create atmosphere, and of 'symbols', (images which take on an expanded function within the poem), betray a move towards considering the poem as a self-referential object, an idea further developed by the Symbolists Verlaine and Mallarmé, who acknowledge Baudelaire as a pioneer in this regard.
On the sidebar you will find a link to the best article ever written in English on Symbolism in literature. It was written by Rene Wellek (1903-1995) the founder of the field of comparative literature in the United States. Professor Wellek created comparative literature at Yale in the 1950's and 1960's. The crowning work of Wellek's career was an eight-volume magnum opus entitled A History of Modern Criticism: 1750-1950, the last two volumes of which he dictated from his bed in a nursing home. This article is taken from the Dictionary of the History of Ideas.
Selected Poems from Les Fleurs du mal: A Bilingual Edition,
University Of Chicago Press,
I would like to recommended to you some great one-volume biography equal to the fine biographies by Frederick Brown on Flaubert and Zola, but alas, no such recent biography exists in English. Therefore I will tell you about this very fine collection of articles on Baudelaire, some of which are excellent. If you are fascinated by him, this volume is the best one to buy in order to continue your studies of Baudelaire.
The Cambridge Companion to Baudelaire,
Cambridge University Press paperback, 2006,