According to John Del Vecchio writing for Fool.com, a value chain is "a string of companies working together to satisfy market demands." The value chain typically consists of one or a few primary value (product or service) suppliers and many other suppliers that add on to the value that is ultimately presented to the buying public.
Microsoft and its Windows operating systems, the nucleus of the personal computer desktop for which much business software is developed, is often cited as a prime example of a company and product that drives a value chain. The businesses who buy personal computer software may spend far more on the add-on software than on the essential operating system that is the de facto standard for running the software. To the extent that companies standardize on Windows, Microsoft is said to control a value chain. This particular value chain was reported in a McKinsey study to be worth $383 billion in 1998. Although Microsoft's share of the value chain was reported to be only 4% of the total, that was still $15.3 billion.
A company that develops a product or service that engenders a value chain by providing a platform for other companies is considered more likely to increase its market share than a company that tries to provide the entire value chain on its own.