Strategy development is the systematic identification and exploitation of the structure of an industry and the competitors in it; it is the identification of actions that can be taken to improve profitability. We apply the methods created by Michael Porter of the Harvard Business School and often called his "Five Forces Analysis."
A good business strategy increases your profitability and makes it difficult for your competitors to react. If they do react, you will have anticipated their action and already have thought through your counteraction.
Business strategy includes effective marketing, but is much more. Often times in includes activities that increase profitability for all competitors in a geographic area or who share a common customer base.