Corporate social responsibility (CSR) is the responsibility corporation have to society. Whether corporations have a responsibility to wider society, and what those responsibilities are, is a matter of some controversy.
At one extreme are those who argue that corporations only have a responsibility to make profits for their shareholders, and wider social issues should be the concern of other organisations, such as governments. This view is often rooted in faith in the "invisible hand" of markets.
Those promoting CSR often talk in terms of stakeholders, who are affected by a company's actions. This relegates shareholders to one of many groups of stakeholder such as employers, customers and communities. Beyond this they will deem companies to have wider responsibilities to society as a whole, such as to minimise damage to the environment.
A common criticism of CSR is that it can be pure PR, and have little real effect of how a business is run. It is true that the businesses that place the most emphasis on CSR are often those with bad images (such as tobacco companies). However, it is also true that many companies have integrated a mission to make the world better deeply into the business (good examples include green businesses, and open source software companies).
CSR look like it is now here to stay. Many investors now use ethical criteria to choose investments, and an increasing number of institutional investors are becoming activist with regard to CSR (as well as other issues).
Business in the Community has information on many aspects of CSR.