Companies
A company is generally defined as a form of business organization. What that means in practice is generally defined by location and tradition. The word actually traces back to the military term which is still in use today, e.g. a "company of soldiers." It then became a term used to refer to trade guilds and eventually by the 16th century was being used as a term for a business association.
There are a wide variety of types of companies with different types of legal rights and responsibilities. Different countries tend to have different attitudes towards companies. In most developed nation there is a concept of a corporation, which is a legal entity that is not a person. This entity has certain limited capacities to function like a person.
Although size and composition vary widely, there are companies all over the world doing tremendously different things. The main tying quality is that they are a group of people working towards the goal of a profit.