Piet Beertema (born 22 October 1943 in Amsterdam) is a Dutch Internet pioneer. On November 17, 1988 at 14:28 hours, he linked the Netherlands as the second country (after the United States) to NSFnet, a precursor to the Internet. Beertema was then working as an administrator at the Centrum Wiskunde & Informatica (CWI) in Amsterdam.
His first job was in 1965 at the Dutch National Aerospace Laboratory, where he first came into contact with a computer (an Elliott 803-B). In 1966 he joined the Center for Mathematics and Computer Science, where he worked until his retirement.
On April 25, 1986 Beertema recorded the first country code top level domain .nl. In 1996 he co-founded the Foundation for Internet Domain Registration Netherlands that would take over the management of the .nl domain, after doing this himself for almost 10 years.
On June 9, 1999 he received a royal decoration, Knight of the Order of the Dutch Lion. On September 16, 2004 he officially retired.
- van Ringelestijn, Tonie (2008-11-17). "20 jaar internet in Nederland en Europa". WebWereld (in Dutch). IDG Nederland. Retrieved 2011-01-24.
Op 17 november 1988, om half drie 's middags, ontving systeembeheerder Piet Beertema van het CWI in Amsterdam het historische e-mailtje waarin stond dat het CWI, als eerste instelling buiten Amerika, was verbonden met NSFnet.