When starting your own business, one of your most important concerns is to develop your company's face to the world. This is your brand. It is the company's name, how that name is visually expressed through a logo, and how that name and logo extend throughout an organization's communications. A brand is also how the company is perceived by its customers — the associations and inherent value they place on your business.
A brand is also a kind of promise. It is a set of fundamental principles as understood by anyone who comes into contact with a company. A brand is an organization's "reason for being"; it is how that reason is expressed through the various communications to its key audiences, including customers, shareholders, employees, and analysts. A brand should also represent the desired attributes of a company's products, services, and initiatives.
Apple's brand is a great example. The Apple logo is clean, elegant, and easily implemented. Notice that the company has altered the use of the apple logo from rainbow-striped to monochromatic. In this way they keep their brand and signal in a new era for their expansive enterprise. Think about how you've seen the brand in advertising, trade shows, packaging, product design, and so on. It's distinctive and it all adds up to a particular promise. The Apple brand stands for quality of design and ease of use.