Americans will cast their votes today in what has been the most technology-intensive US presidential campaign ever.

The election brings to a close a series of state and local campaigns which have been shaped by the internet and the companies behind the industry.

Starting as early as 2007, candidates were addressing such issues as software patent reform, while the primary season saw the first presidential debates to be broadcast on YouTube.

As the campaign marched on, the web took an increasing role. Barack Obama launched an anti-smear website designed to debunk personal attacks, while his name was used by cyber-criminals to create their own attacks.

Rival John McCain had a slightly bumpier road on the web. The republican candidate generated unwanted headlines when an aide suggested that McCain had helped to create the BlackBerry.

McCain later became tied up in a battle with YouTube over takedown claims made on his campaign videos.

The people behind many of the biggest names in IT also became involved in the campaign. Former HP chief executive Carly Fiorina and former eBay chief executive Meg Whitman both lined up behind McCain, while eBay chief executive Eric Schmidt endorsed Obama.

A survey in March found that IT workers themselves were evenly split between the two candidates.

Silicon Valley also became involved in state elections. Apple and Google publically came out in opposition to California's proposed ban on gay marriages, while dozens of industry executives signed a petition urging voters to crush the controversial proposition.