Flickr is a popular photo sharing website that allows members to upload their own photos into customizable albums that can then be labeled, organized, tagged, and publicly posted. Flickr, as well as many other photo hosting websites, provides image URLs for every file that is uploaded, and these image URLs can then be used to embed a photo in a website, a social media profile, blog post, or email.

Before Flickr came along, sharing photos meant a laborious and sometimes not very user-friendly process of creating albums, uploading them, and devising a means for people to navigate between them.

Indeed, the whole concept of posting photos to the web was still based on the idea that they should come in a set, a collection called an “album.” Digital photography doesn’t work like that; we no longer process rolls of film, nor do we have to file away groups of images in album-sized collections.

Posting photos online needed a new approach, and the team at Flickr worked out what it should be.

At Flickr (for anyone who has never visited the site), the single image is the basic unit of photo sharing. Sure, images can be grouped together (into “sets” rather than “albums”) and viewed as a group in a slideshow, but there’s no need to do that. Rather, images can be added as and when they are taken. If you’ve just taken one good shot today, you only need upload that. If you’ve taken 30, you can upload them all. It doesn’t matter.

Flickr’s database structure means that every image is associated with its creator or owner first, then with any groups or sets it might have been added to, then with any free-text tags that might have been assigned to it, and finally with the electronic metadata that the camera added to the original snapshot.

Flickr is one of those ideas that depends on interconnectivity. Your pictures are of interest to your contacts; your weather pictures are of interest to other users of the weather photos group. Your “weather” tag shows up in the RSS readers of others with the same interest. While you forgot to add the “weather” tag to that great shot of a cloud you took the other day, you did remember to add “cloud,” which means the image shows up alongside other clouds. Some passing stranger helps you out by adding the “weather” tag for you anyway.