Social bookmarking web service for storing, sharing, and discovering web bookmarks. The site was founded by Joshua Schachter in late 2003, and was acquired by Yahoo! in 2005. Now it has more than three million users and 100 million bookmarked URLs.

Facebook is a social utility that connects people with friends and others who work, study and live around them. People use Facebook to keep up with friends, upload an unlimited number of photos, share links and videos, and learn more about the people they meet.

Flickr – almost certainly the best online photo management and sharing application in the world –

has two main goals:

1. We want to help people make their photos available to the people who matter to them.

2. We want to enable new ways of organizing photos.