Logo, Trade Mark, Brand is known as an identity of a company. In simple language a logo is a graphical element that represents Company Brand or trademark (when registered). In general a logo is designed for immediate recognition. The logo is one which is required for developing company's commercial brand or academic entity. They are supposed to be designed in different shapes, colors, fonts, and images from others in a similar market. To remember name of company or the owner for all articles being sold in market is not possible, but one can recognize the logo easily and can have trust on that brand.
Every company, institutes, corporations, agencies, manufacturers has their brand (developed by their quality of product, work experience, service) defined by an icon can be registered legally and being known as trademark. After such registration other can not sell or do similar activities by similar icons or logos.
Logo is a very important for developed companies and can not be changed frequently as people know the company by logo (brand). So it is advisable to design a logo before the company is developed and being recognized by the logo. Logo has sentimental relationship with the owner and sensible relationship with the customers. So we always take care while designing the logo from both the aspects. Concept is important for designing the logo.