Historically, the term business referred to activities or interests. By extension the word became (as recently as the 18th century) synonymous with "an individual commercial enterprise". It has also taken on the more general meaning of "a nexus of commercial activities".
People establish businesses in order to perform economic activities. With some exceptions (such as cooperatives, corporate bodies, non-profit organizations and institutions of government), businesses exist to produce profit. In other words, the owners and operators of a business have as one of their main objectives to receive or generate a financial return for their time, effort and capital.
An industry can consist of a group of related businesses, such as the entertainment industry or the dairy industry. This definition resembles one of the more general meanings of "business", and the terms business and industry sometimes appear interchangeable. Thus a fisherman might say either (more colloquially) that he is in the "fishing business" or (somewhat grandiosely) that he works in the "fishing industry". Similarly, the word "trade" may serve as an equivalent of both "business" and "industry": Victorians might despise those "in trade", and one can still refer to working "in the rag trade", for example.
"Whoever could make two ears of corn or two blades of grass to grow upon a spot of ground where only one grew before would deserve better of mankind and do more essential service to his country than the whole race of politicians put together." - Jonathan Swift