Social bookmarking uses any of several web sites to store and share internet bookmarks.
For the end user, this has several advantages. Firstly, it allows you to access your bookmarks from any computer in the world that has access to the internet. Secondly, it lets you share web sites you like, and find sites that other people like. Thirdly, some people prefer the categorisation and organisation options provided by social bookmarking sites over those of their browsers; delicious, for instance, was allowing users to tag their bookmarks long before Firefox was. Finally, social bookmarking ties in with the more general concept of social networking - you can find other people who like the same sorts of sites as you, keep up with sites your friends have been enjoying, and so on.
Everything2, like many other web sites, now provides a set of social bookmarking buttons, which by default are located at the bottom of writeups. These make it slightly easier to submit pages to bookmarking sites, although their main role is really to encourage pages to be added, not so much to facilitate it. Everything2's buttons will also send a message to the user whose writeup is being bookmarked (subject to opt-outs in User Settings, where you can also prevent them from showing up on your own writeups).
In general the writeup won't be submitted as soon as you press the button. Naturally you'll need to log in to the site in question if you haven't already, and usually you'll also need to fill in a short form where you can describe and classify the page. This means that in some cases the message will be a little misleading, since it is sent as soon as the button is pressed, but that's hard to avoid.
Social bookmarks are a major driver of internet traffic now; on most of the sites that I've had a hand in administrating over the last few years, they've been second only to search engines in bringing people in to a site. In some sense they are just a formalisation of what the very first web logs were - easy ways for people to share web sites that they like - and indeed, there is considerable overlap between blogging and social bookmarking. Typically the list of someone's social bookmarks is structured very much like a blog, and it is not uncommon for people to include feeds of their favourite links in their general-purpose blogs.
At the moment E2 shows a list of six bookmarking sites:
- Delicious.com (formerly del.icio.us) is almost certainly the single biggest social bookmarking site. Its design is sparse, with little colour and not much in the way of images. Was at the forefront of the move to use 'tagging' as an organising principle for the internet. Bought by Yahoo! in late 2005.
- Furl.net is another of the big players, though it seems less popular than it was for a while, perhaps because they never added very much in the way of categorisation - no tags here, at least as far as I can tell. Includes surprisingly little commentary on submitted URLs.
- Facebook, the social networking behemoth, has social bookmarking as one of its many afterthoughts, and because it is so enormous, this makes it one of the major social bookmarking sites. A little frustratingly, the site's privacy options mean that in most cases it is impossible to see who might be saying what about your page on there, unless you happen to know them.
- Digg apparently started out being all about 'news for geeks', but now it calls itself 'a place for people to discover and share content from anywhere on the web'. It remains largely news-focused though, and care should be taken when submitting anything that couldn't be described as news.
- Reddit remains overwhelmingly about news, though they do invite you to submit links 'to anything interesting: news article, blog entry, video, picture...' Like Digg, it's very much more about sharing links than it is about storing bookmarks for your own benefit, and it shows a strong bias towards recent submissions.
- StumbleUpon is focused on a 'Stumble' button, designed to bring up a random web page you're likely to find interesting based on your stated interests and things you've told it you like (or dislike) before. No particular slant towards any one kind of content, and because their algorithms are based on popularity without regard to novelty, pages which prove popular can receive huge numbers of visitors for a very long time. SU also has more of a networking bent than most of these sites, and more options for personalisation.
These are just six of many - some specialised, some very general. It was tricky to pick which ones to include, and the selection is potentially subject to change; the code already includes the option to show a list of around 15, which appear in the Social Bookmarking nodelet. Incidentally, the only one of these that I have made extensive use of is StumbleUpon, where you can find me as fergusmurray, so my notes on the others are based on not much more than skimming their surface.