Originally, individual trades people were qualified, and they hired assistants. The invention of the joint-stock company meant a new era in business. By this means, some people put up the money as capital, and others used it to run the business. There is a law which says this kind of company is a "legal entity": it has a legal life separate from its owners or shareholders. In this way, a company can outlive the people who started it. This idea was invented in medieval times, but really flowered in the 19th century. It has spread around the world since then.