A product line is a group of related products of one company.  The products are usually tied together by means of a company logo or brand.  For instance, Nike sells shoes, sports apparel and sports equipment.  Every item they sell has the distinctive Nike logo on it. While function is one way to differentiate product lines, they can also be separated based on gender and age.  Within Nike’s shoe line are shoes for children, adult men and adult women.  Those lines are further differentiated based on functions, such as shoes for walking, running, cross training, basketball, football, baseball, soccer and golf. Product lines are a good way for companies to leverage existing brand recognition to increase market share and revenue.  If a company has a trusted, recognizable brand, it is much easier for them to enter a market and gain market share.  Loyal customers, familiar with the brand from another market, will be more inclined to buy the company’s new product line.  This helps the company save on marketing and advertising expenses it would otherwise incur when building a new product line without any brand recognition. For example, assume Giacomo’s Pizza is a popular, established brand in the frozen pizza market.  If Giacomo develops a new line of calzones, the company can benefit from its existing brand loyalty by calling the new line Giacomo’s Calzones.  They save money on building brand awareness, and also have a pre-existing customer base among those who already buy their pizzas.