Market share is the percentage of the total market that a company's products or services represent. It's calculated by dividing a company's sales by the total sales of all companies in the same market. For example, if a company sells $100 million worth of products and the total market sales are $1 billion, then the company's market share would be 10%. Market share is important because it helps companies understand their competitive position and how they compare to their competitors. It also helps companies gauge their growth potential and set realistic goals for market penetration. Companies with high market share typically have a strong brand, loyal customers, and a competitive advantage.