Internet icons: Something to say? Button it

If you've read something online and want to pass it on, it's easy, says Gillian Orr. Just learn to use the icons

The internet, despite being the place where many of us spend many hours shopping, swotting and socialising, still has the power to baffle. Browsing an article on a news website, you may have noticed that it is accompanied by a clutch of icons at the bottom. What do these brightly coloured hieroglyphs stand for? And what do they add to your online reading experience?

Some are obvious; there's "print" and "comment" and "email". But things get more complicated when you click on "share". Then a selection of logos and options appear. Some you will recognise, such as Facebook or MySpace, but to the uninitiated, some might be a bit more unfamiliar, names like Digg, Mixx or Reddit.

These allow you to share the story you're looking at with friends, colleagues, or strangers through that particular website. And it has a name – social bookmarking. This is a loose term for the organising, sharing and storing of online pages. You share the link to a page, not the contents of the page, therefore it's different to file sharing. Metadata (or data about data) is added to your bookmarking, which could mean including your own text description, voting in favour of the piece's quality or adding tags to it so others with similar interests can find it. It is then shared in the network you subscribe to.

The idea of organising and managing links systematically rather than just listing them dates to 1996 with the launch of itList, which let users share bookmarks privately and publicly. In 2003, del.icio.us launched (later renamed Delicious), coining the term "social bookmarking" and pioneering tagging.

If you're looking for articles on, say, Mad Men, you would benefit from searching on a social network or sharing site for tagged articles about it because the articles will have been put there by humans, and your responses will be more sophisticated than a search engine. However, human error causes incorrectly spelt tags. Corruption is rife, too. Some people use tagging on social bookmarking to make their website more likely to be found. Despite this, social bookmarking and sharing remains a remarkable way to distribute information on the internet.