An organic compound is virtually any chemical compound that contains carbon, although a consensus definition remains elusive and likely arbitrary. Organic compounds are rare terrestrially, but of central importance because all known life is based on organic compounds. The most basic petrochemicals are considered the building blocks of organic chemistry. 

For historical reasons discussed below, a few types of carbon-containing compounds, such as carbides, carbonates, simple oxides of carbon (for example, CO and CO), and cyanides are considered inorganic. The distinction between "organic and inorganic" carbon compounds, while "useful in organizing the vast subject of chemistry... is somewhat arbitrary". 

Organic chemistry is the science concerned with all aspects of organic compounds. Organic synthesis is the methodology of their preparation. 

For many centuries, Western physicians and chemists believed in vitalism. This was the widespread conception that substances found in organic nature are created from the chemical elements by the action of a "vital force" or "life-force" ("vis vitalis") that only living organisms possess. Vitalism taught that these "organic" compounds were fundamentally different from the "inorganic" compounds that could be obtained from the elements by chemical manipulations. 

Vitalism survived for a while even after the rise of modern ideas about the atomic theory and chemical elements. It first came under question in 1824, when Friedrich Wöhler synthesized oxalic acid, a compound known to occur only in living organisms, from cyanogen. A more decisive experiment was Wöhler's 1828 synthesis of urea from the inorganic salts potassium cyanate and ammonium sulfate. Urea had long been considered an "organic" compound, as it was known to occur only in the urine of living organisms. Wöhler's experiments were followed by many others, in which increasingly complex "organic" substances were produced from "inorganic" ones without the involvement of any living organism.
What is the main topic of this article?
Organic chemistry is the science concerned with all aspects of organic compounds. Organic synthesis is the methodology of their preparation