Logo design also known as brand identity is the last step in a strategic creative process of visually separating your company from others in your field. As message, it reflects your value proposition and the values that satisfy your customers.
Have a look as at "The Art of Logo Design - Off Book - PBS.
It examines the strategic and artistic thinking that goes into the design of a strategic, singular, memorable, extendable visual identity for companies and organizations of all types. At its essence, it is a picture that speaks 10,000 words.