Early versions of Flickr focused on a multiuser chat room called FlickrLive with real-time photo exchange capabilities. There was also an emphasis on collecting images found on the web rather than photographs taken by users. The successive evolutions focused more on the uploading and filing backend for individual users and the chat room was buried in the site map. It was eventually dropped as Flickr's backend systems evolved away from the Game Neverending's codebase.
Some of the key features of Flickr not initially present were tags, marking photos as favorites, group photo pools and interestingness, for which a patent is pending.
In March 2005, Yahoo! acquired Ludicorp and Flickr. During the week of June 28, 2005, all content was migrated from servers in Canada to servers in the United States, resulting in all data being subject to United States federal law.
On May 16, 2006, Flickr updated its services from beta to "gamma", along with a design and structural overhaul. According to the site's FAQ, the term "gamma", rarely used in software development, is intended to be tongue-in-cheek to indicate that the service is always being tested by its users, and is in a state of perpetual improvement. For all intents and purposes, the current service is considered a stable release.
In December 2006, upload limits on free accounts were increased to 100MB a month (from 20MB) and were removed from Pro Accounts, permitting unlimited uploads for holders of these accounts (originally a 2GB per month limit).
In January 2007, Flickr announced that "Old Skool" members--those who had joined before the Yahoo acquisition--would be required to associate their account with a Yahoo ID by March 15 to continue using the service. This move was criticized by some users.
On April 9, 2008, Flickr began to allow paid subscribers to upload videos limited to 90 seconds in length and 150MB in size.
Flickr asks photo submitters to organize images using tags (a form of metadata), which allow searchers to find images concerning a certain topic such as place name or subject matter. Flickr was also an early website to implement tag clouds, which provide access to images tagged with the most popular keywords. Because of its support for tags, Flickr has been cited as a prime example of effective use of folksonomy, although Thomas Vander Wal suggested Flickr is not the best example.
Flickr also allows users to organize their photos into "sets", or groups of photos that fall under the same heading. However, sets are more flexible than the traditional folder-based method of organizing files, as one photo can belong to one set, many sets, or none at all. Flickr's "sets", then, represent a form of categorical metadata rather than a physical hierarchy. Sets may be grouped into "collections", and collections further grouped into higher-order collections.
Finally, Flickr offers a fairly comprehensive web-service API that allows programmers to create applications that can perform almost any function a user on the Flickr site can do.
In November 2006 Flickr created a "guest pass" system that allows private photos to be shared with non Flickr members. For instance, a person could email this pass to parents who may not have an account to allow them to see the photos otherwise restricted from public view. This setting allows sets to be shared, or all photos under a certain privacy category (friends or family) to be shared.
In March 2007, Flickr added new content filtering controls that let members specify by default what types of images they generally upload (photo, art/illustration, or screenshot) and how "safe" (i.e., unlikely to offend others) their images are, as well as specify that information for specific images individually. In addition, users can specify the same criteria when searching for images. There are some restrictions on searches for certain types of users: non-members must always use SafeSearch, which omits images noted as potentially offensive, while members whose Yahoo! accounts indicate that they are underage may use SafeSearch or moderate SafeSearch, but cannot turn SafeSearch off completely.
Many members allow their photos to be viewed by anyone, forming a large collaborative database of categorized photos. By default, other members can leave comments about any image they have permission to view, and in some cases can add to the list of tags associated with an image.
The core functionality of the site relies on standard HTML and HTTP features, allowing for wide compatibility among platforms and browsers. Organizr uses Ajax, with which most modern browsers are compliant, and most of Flickr's other text-editing and tagging interfaces also possess Ajax functionality. Images can be posted to the user's collection via email attachments, enabling direct uploads from many cameraphones and applications with email capabilities. Flickr has increasingly been adopted by many web users as their primary photo storage site, especially members of the weblog community. In addition, it is popular with Macintosh and Linux users, who are locked out of photo-sharing sites that require Windows and Internet Explorer.
Flickr uses the Geo microformat on the pages for over 3 million geotagged images.
Flickr partners with third parties to offer streamlined printing of various forms of merchandise, including business cards, photo books, and large size prints.
Users of Windows Live Photo Gallery now have the ability to upload their photos directly to Flickr.
Flickr has since used this setting to change the level of accessibility to "unsafe" content for entire nations, including South Korea, Hong Kong, and Germany. In summer 2007, German users staged a "revolt" over being assigned to the user rights of a minor. See Censorship controversy below.
The filter system of Flickr assumes that photos may be unsafe and should not be public until a staff person has validated that the material is safe. Until this happens, which could take up to a month, material cannot be viewed by persons without a valid Yahoo and Flickr account. A Flickr site not marked as safe can only be viewed by people in the community who have set their filters beyond the default status of that of a “minor”.
On June 12 2007, in the wake of the rollout of localized language version of the site, Flickr implemented a user-side rating system for filtering out potentially controversial photos. Simultaneously, users with accounts registered with Yahoo subsidiaries in Germany, Singapore, Hong Kong, and Korea were prevented from viewing photos rated "moderate" or "restricted" on the three-part scale used. Many Flickr users, particularly German, protested against the new restrictions, claiming unwanted censorship from Flickr and Yahoo.
Flickr management, unwilling to go into legal details, implied that the reason for the stringent filtering were unusually strict age-verification laws in Germany. The issue received some attention in the German national media, especially in online publications. Initial reports indicated that Flickr's action was a sensible, if unattractive, precaution against prosecution, although later coverage implied that Flickr's action may have been unnecessarily strict.
On June 20 2007 Flickr reacted by granting German users access to "moderate", but not "restricted" images, and hinted at a future solution involving advanced age-verification procedures for Germany, though no mention was made of Singapore, Hong Kong or Korea.
Flickr is also blocked by the governments or ISPs of some countries. An example is the UAE provider Etisalat.
Users in mainland China are no longer blocked by Chinese ISPs.
On November 27, 2007, Chang filed for a voluntary dismiss of the lawsuit against Creative Commons, focusing their lawsuit against Virgin Mobile. , the lawsuit is still pending