[citation needed] He also worked at the National Center for Supercomputing Applications (NCSA) at the University of Illinois, where he became familiar with Tim Berners-Lee's open standards for the World Wide Web.

[6] In the Web's first generation, Tim Berners-Lee launched the Uniform Resource Locator (URL), Hypertext Transfer Protocol (HTTP), and HTML standards with prototype Unix-based servers and browsers.

Several million then suddenly noticed that the Web might be better than sex.Andreessen has worked at Netscape, Opsware, founded Andreessen Horowitz, and invested in many successful companies including Facebook, Foursquare, GitHub, Pinterest, LinkedIn, and Twitter.

Clark believed the Mosaic browser had great commercial possibilities and suggested starting an Internet software company.

Soon, Mosaic Communications Corporation was in business in Mountain View, California, with Andreessen as co-founder and vice president of technology.

[14] After AOL acquired Netscape in late 1998, Andreessen founded Opsware with Ben Horowitz, Tim Howes, and In Sik Rhee.

[18] Andreessen Horowitz began with an initial capitalization of $300 million;[19] within three years the firm grew to $2.7 billion under management across three funds.

[25] In October 2014, he announced his resignation from the board due to the company's decision to break off its online payments unit PayPal.

Icahn published his argument in an open letter that detailed alleged conflicts of interest in eBay's 2009 sale of Skype to a group of private investors, which included Andreessen's firm.

[37] In April 2020, early in the COVID-19 pandemic, Andreessen published an opinion article, "It's time to build", describing the United States' COVID-19 response and suggesting technological and cultural solutions to the problem.

[44] Andreessen serves on the board of Meta,[45] Hewlett Packard Enterprise, Kno,[46] Stanford Hospital,[47] Bump Technologies, Anki,[48] Oculus VR,[49] OpenGov,[50] Dialpad, and TinyCo.

[51] Hewlett Packard Enterprise announced in February 2018 that board member Andreessen would not seek reelection at the 2018 Annual Meeting of Stockholders on April 4.

[52] In his time at Hewlett Packard, Andreessen had been partially blamed for some of the company's failures, including the recruiting of Léo Apotheker as well as the acquisitions of Autonomy and Palm.

[56] Andreessen is on an advisory board for Neom, the Saudi Arabian government's plan to build a futuristic megacity in the desert.

[57][58] In February 2016, Andreessen posted a tweet in response to India's decision to apply net neutrality to Facebook's proposed project Free Basics.

Andreessen later deleted the tweet following criticism from Indians and non-Indians alike (including Facebook founder Mark Zuckerberg).

In 2009, Andreessen issued a $25,000 reward for information leading to a conviction in the 1987 unsolved murder of Barbara Blackstone, a teacher from New Lisbon High School in Wisconsin, where he had attended.

[80] Andreessen came out against president Joe Biden's re-election bid, saying he feared higher taxes on billionaires and stricter regulations on industries he invests in (cryptocurrency and AI).