This guide is based on UK law. It was created in February 2007.
Flickr.com became a huge success by offering a free platform for uploading digital photographs. Users tag each picture that they upload to provide a description that helps other users navigate the site.
Tagging is a form of meta data – in this case meaning data describing a web page of image – and raises the same issues: if someone deliberately tags content with a registered trade mark to attract web traffic, it could amount to trade mark infringement. (See: The use of trade marks in meta tags)
There is also a tough criminal penalty in the US if the use of words might lead anyone to obscene content. The Adam Walsh Child Protection and Safety Act, passed in July 2006, introduces a 20-year maximum prison sentence for this form of meta tag abuse. It is targeted at those sites using words that would attract children to pornographic content.
See also: Legal info about user-generated content