Social network aggregation
Social network aggregation is the process of collecting content from multiple social network services into one unified presentation. The task is often performed by a social network aggregator (such as Hootsuite and FriendFeed), which pulls together information into a single location,  or helps a user consolidate multiple social networking profiles into one profile.  Various aggregation services provide tools or widgets to allow users to consolidate messages, track friends, combine bookmarks, search across multiple social networking sites, read RSS feeds for multiple social networks, see when their name is mentioned on various sites, access their profiles from a single interface, provide "lifestreams", and so on.  Social network aggregation services attempt to organize or simplify a user's social networking experience,  although the idea has been satirized by the concept of a "social network aggregator aggregator". 
There are other related uses of social media aggregators aside from simplifying the user's social networking experiences. Some aggregators are designed to help companies and individuals improve engagement with their brands by creating aggregated social streams that can be embedded into an existing website and customized to look visually intrinsic to the site. This allows potential customers to interact with all the social media posts maintained by the brand without requiring them to jump from site to site. This has the benefit of keeping customers on the brand's site for a longer period of time.
Social network aggregation platforms allow social network members to share social network activities like Twitter, YouTube, Stumbleupon, Digg, Delicious, with other major platforms. All content appears in real time to other members who subscribe to a particular community, which eliminates the need to jump from one social media network to another, trying to keep an eye on one's interests. 
Social network aggregation systems can rely on initiation by publishers or by readers. In the publisher-initiated aggregation systems, the publishers combine their own identities, which make their readers see all aggregated content once subscribed. In the reader-initiated systems (such as Windows Phone 7 people hub  and Linked Internet UI ), the readers combine the identities of others, which has no impact on the publishers or other readers. The publishers can still keep separate identities for different readers.
Technically, the aggregation is enabled by APIs provided by social networks. For the API to access a user's actions from another platform, the user will have to give permission to the social-aggregation platform, by specifying the user-id and password of the social media to be syndicated. This concept resembles open ID.  In March 2008, The Economist reported that social network services are only beginning the move away from "walled gardens" to more open architectures. Some sites are working together on a "data portability workgroup", while others are focusing on a single sign-on system called OpenID to allow users to log on across multiple sites. Historically, the trend from private services to more open ones can be seen across many Internet services from email and instant messaging to the move that early online service providers made to become websites.  The OpenSocial initiative aims to bridge the member overlap between various online social network services. 
Social network aggregators such as FriendFeed represent connexion between people throughout directed graphs. They adopt a following approach, rather than a friending one, where “A follows B” does not imply “B follows A”. Each account is then represented by a node whereas the following relationship is represented by an edge. The relationships between these nodes appear to be linked to their age and their sphere of influence. Indeed, the nodes which have joined the network most recently get less influence than older ones. Therefore, on social network aggregators, new nodes tend to connect to nodes with high degrees. 
Historically, social media aggregators have always existed. Indeed, newspapers act in that way: journalists summarize numerous pieces of information and try to bring relevant content from many sources, in a synthesized and understandable way. The purpose is to provide understable information for everyone about more or less complex topics so that people will not have to spend hours finding and analyzing news from all around the world. Moreover, it was also an aggregator for job offers and other type of ads. 
Performing social networks aggregation requires a large range of data. First, the relevant content related to a topic and then the information about the profiles that have been reached by the content. The added value of social network aggregation is to analyze the data. They provide a correlation between the audience profiles (preferences, interests, age, location...) and the type of the content. However, collecting such data may be difficult. Databases of social networks are rather different and may change during some updates. 
Social network aggregators are a powerful tool in marketing. They appear to be an efficient way to have an organized view of the content to get a better insight into the market. The needs about them are real: a study provided by eMarketer  shows that 43% of marketers are complaining about a significant lack of time to find relevant content for their business. Social network aggregators grant features to share your own content in many social media to reach as many people as possible. That way, social network aggregators become a productivity enhancement tool.  A list of some example social media aggregators for brands can be found here.
The attraction of social network aggregation comes from the fact that some users tend to use multiple social networks: they have accounts on several social-networking sites.  In November 2007, Alex Patriquin of Compete.com reported on the member overlap between various online social network services: 
- List of social networking websites
- Social media
- Social network
- Social network consolidator
- Social network service
- Web 2.0
- Rachael King (2007-06-18). "When Your Social Sites Need Networking". BusinessWeek. Retrieved 2008-04-10.
- Stan Schroeder (2007-07-17). "20 Ways To Aggregate Your Social Networking Profiles". Mashable. Retrieved 2008-04-10.
- Beth Snyder Bulik (2007-06-18). "Upstart websites aim to consolidate social networking".
The latest trend in the space is aggregation-websites...[which] all present variations on the theme of organizing or simplifying a consumer's social-networking experience.
- Brian Briggs (2008-03-17). "Social Network Aggregator Aggregator AllMyFrickingFriends.com Launched". BBSpot. Retrieved 2008-04-10.
- "Social Aggregation: defragment your online life". April 1, 2008. Archived from the original on December 29, 2009.
- Microsoft. "Windows Phone 7 Features". Microsoft. Retrieved 2011-11-11.
- Nokia (2009-09-02). "Linked Internet UI Concept". Nokia. Retrieved 2011-11-11.
- David Jennings (2005-08-03). "Aggregation of data across social networks". alchemi.co.uk. Retrieved 2008-04-10.
- "Everywhere and nowhere". The Economist. 2008-03-19. Retrieved 2008-04-10.
- Alex Patriquin (2007-11-12). "Connecting the Social Graph: Member Overlap at OpenSocial and Facebook". Compete.com blog. Retrieved 2008-04-10.
- Evolution of an Online Social Aggregation Network: An Empirical Study http://www.cs.ucsb.edu/~trinabh/papers/imc09.pdf
- Increasing social network productivity through aggregation https://www.godaddy.com/garage/increasing-social-network-productivity-through-aggregation/
- Virmani, C.; Pillai, A.; Juneja, D. (February 2014). "Study and analysis of Social network Aggregator". 2014 International Conference on Reliability Optimization and Information Technology (ICROIT): 145–148. doi: 10.1109/ICROIT.2014.6798314. ISBN 978-1-4799-2995-5.
- Half of Marketers Believe Programmatic Is Effective, Jun 27, 2018, https://www.emarketer.com/content/half-of-marketers-believe-programmatic-is-effective
- "Who Uses Social Networks and What Are They Like? (Part 1)". ReadWriteWeb. July 9, 2009. Archived from the original on June 22, 2012. Retrieved September 6, 2013.