1) A company is defined as an artificial legal entity created under the Companies Act for the purpose of earning profits or achieving charitable goals. 2) There are five main types of companies - chartered, statutory, registered, private, and public. Private companies have 2-200 members while public companies require a minimum of 7 members. 3) Key characteristics of companies include separate legal identity, limited liability, perpetual succession, ability to own property, transferability of shares, and use of a common seal.