Marc Andreessen is an American entrepreneur, investor, and software engineer, best known for co-founding Netscape, one of the first web browsers, in the 1990s. He played a significant role in popularizing the internet and has been influential in the tech industry ever since. In addition to his work with Netscape, Andreessen co-founded Andreessen Horowitz, a prominent venture capital firm that invests in technology startups. He has invested in several successful companies, including Facebook, Twitter, and Airbnb, and is recognized for his insights on technology and innovation.