Objectivism is a philosophy presented by the Russian-American novelist and philosopher Ayn Rand in her books and writings, especially The Fountainhead (1943) and Atlas Shrugged (1957). Over 22 million of her books have been sold worldwide as of 2005, with half a million more being sold every year. Rand was one of the most influential philosophers of the 20th century, and her ideas and values form a large part of the foundation of the modern-day libertarian movement. Although Objectivism was at its height throughout the 50s, 60s, and 70s, today there are probably several tens of thousands of people who self-identify as being part of the Objectivist movement, which promotes Objectivism in various ways and, like any movement, also serves as an international social club.
With Objectivism, what began as a few books and writings expanded into a formal philosophy and associated institute that rebelled against some of the popular ideas of the time while concurring with others. For example, Rand's philosophy was atheistic, yet also anti-Communist. In the appendix of what is often considered Rand's greatest and most comprehensive work, Atlas Shrugged, Rand sums up Objectivism in a single sentence: "My philosophy, in essence, is the concept of man as a heroic being, with his own happiness as the moral purpose of his life, with productive achievement as his noblest activity, and reason as his only absolute."
The name Objectivism comes from one of the first principles of the philosophy - there is one objective reality, which we all have our own imperfect sensory window into. This is called metaphysical realism, and is a tenet of many other philosophies and belief systems. Rand and modern-day Objectivists believe in an objective set of ethics as well, in the form of rational self-interest. Hence, Objectivism is against altruism and other forms of egoistically unjustifiable self-sacrifice.
Like some of the ancient Greek philosophers by which Rand was influenced, Objectivism's epistemology, its account of where truth comes from, focuses on reason. By extension, this supports science above superstition and places emphasis on the power of industry. Objectivists are not religious.
Politically, Objectivism is extremely capitalistic and seeks to minimize governmental influence over private industry and business. It was a good philosophy to guide people in America and other countries in the decades after WWII, when progress was greatly accelerated and quality of life was drastically improved by industry and capitalism. Aesthetically and artistically, Objectivism adheres to Romantic Realism, which focuses on the power of human volition and choice in how we conceive of ourselves and interact with the world. Objectivists dismiss excessive emotion or sentimentality, which they point out can get in the way of one's self-interest or ability to think logically.
Ayn Rand died in 1982, but her philosophy lives on through organizations such as the Ayn Rand Institute and the Atlas Society, and in informal and formal discussions held by philosophers and students around the globe.