1964 Major works Von Hippel has published three books to date. All are published under Creative Commons licenses, and electronic copies can be obtained by anyone at no cost. These books are titled (1) The Sources of Innovation (1988); (2) Democratizing Innovation(2005); and Free Innovation (2017). Major topics covered in these books and also in many research articles follow. Innovation by lead users User innovation occurs when individuals or firms that actually use a product or service develop what they need for themselves. This is in contrast to producer innovation, where firms develop products for sale to users. Eric von Hippel was one of the first to explore this phenomenon in depth. He found that innovation by users differed from innovation by producers in a number of important ways. For example, products developed and sold by producers are typically intended to profitably serve the average needs of a wide range of people, and therefore may fit the needs of specific customers only approximately. In contrast, users develop or modify products to fit their own needs very precisely. von Hippel coined the term "lead users" to describe innovating users with needs that are ahead of the general market. Lead users are a very important source of innovative progress because they often pioneer - acting earlier than producers to develop important new types of products and applications. Being innovation pioneers pays for lead users because they innovate only to serve their own needs. For this reason, they need not concern themselves with whether others will also want what they are developing for themselves. In contrast, producers must wait for evidence that there is a general and profitable market to be served before they can justify investing in a new type of innovation. For example, mountain bikes were developed by individuals who simply wanted to bike down mountains for fun, and so invented the sport of mountain biking for themselves. Bike producers stood by, simply watching and waiting for years until the extent of the market became clear. Finally, after the new sport had spread to hundreds of enthusiasts who participated by building their own "clunker" mountain bikes, producers finally entered the new market with the first commercial mountain bike products Studies of 1,678 innovations in nine industries find that lead users were the pioneering developers of 54.4% of those judged most important over time. User innovation activity appears to be present in