1. Online Social Networks Modified from Philipa Gill CPE 401 / 601 Computer Network Systems Mehmet Hadi Gunes

2. Basic definitions Network: (net + work, 1500’s) Noun: – Any interconnected group or system – Multiple computers and other devices connected together to share information Verb: – To interact socially for the purpose of getting connections or personal advancement – To connect two or more computers or other computerized devices

3. What is a Social Network ? Network – a set of nodes, points or locations connected Social Network - a social structure made up of individuals (or organizations) called "nodes", which are tied (connected) by one or more specific types of interdependency, such as friendship, common interest Online Social Networks – Platforms to build social networks among people who share interest, backgrounds, or real life connections Source: Wikipedia 3

4. What are (Online) Social Networks? Social networks are graphs of people – Graph edges connect friends – `Friend’ has different implications – How hard is it to be Facebook `friends’? Online social networking – Social network hosted by a Web site – Friendship represents shared interest or trust – Online friends may have never met

5. http://soshable.com/twitter-vs-facebook-across-the-web/ Facebook – befriend me Twitter – I follow you; you follow me Flickr – ‘just post it’ Friendship Establishment 5

6. Social Networks Links denote a social interaction – Networks of acquaintances – collaboration networks actor networks co-authorship networks director networks – phone-call networks – e-mail networks – Bluetooth networks – sexual networks – home page/blog networks –…–…

7. Popular social networking sites Art – devianART General – Facebook, Google+, Qzonr Microblogging – Twitter, Reddit, Sina, Tumblr Movies – flickster, YouTube Music – last.fm, Vkontakte Personal sites – Myspace, Mylife, Cyworld Photos/pictures – Flickr, Instagram, Pinterest Professional – LinkedIn, Academia Relationship initiation – Friendster 7

8. Social Network Usage 8

9. Social Media is Consumer generated media It is media that is designed to be shared, sharing means that it is easy to comment on, that it is easy to send, there are no costs associated with viewing the media and last but not least it is always available. Social media enables people to share information with friends and colleges using the Internet

10. Social Networking

11. Social Network Statistics 11 Facebook – Worldwide, there are over 1.19 billion active Facebook users Source: Facebook – 4.5 billion likes generated daily as of May 2013 which is a 67 percent increase from August 2012 Source: Facebook – There are 874 million mobile active users which is a 45 percent increase from 2012 Source: Facebook – 50% of 18-24 year-olds go on Facebook when they wake up Source: The Social Skinny – One in five page views in the United States occurs on Facebook Source: Infodocket 2012

12. Social Network Statistics Twitter – 230+ million monthly active users – 500 million Tweets are sent per day – 76% of Twitter active users are on mobile Google+ – ~ 540 million registered users, 300 million people active in stream – Over 1.5 Billion photos uploaded every week to Google+ photos 12 Linkedin – More than 259 million members in over 200 countries – Professionals are signing up to join LinkedIn at a rate of more than two new members per second Instagram – Over 100 million users, – total, 40 million photos are uploaded to Instagram every single day according to a report by Nielsen.

13. Online social network use Fixed broadband (Sandvine Q1 2014) YouTube 5.5% upload, 13.2% down Facebook 2.2% upload, 2.0% down Popular with users on the go – Mobile (Sandvine Q1 2014) YouTube 3.8% up, 17.6% down Facebook 27.0% up, 14.0% down 13

14. Social Networks Not a new concept, (6 degrees of separation) People typically maintain 10-20 close relationships among thousands of acquaintances The vast majority of people report the opinion they trust most is from ‘someone like me’. – For the first time in our history, peers have bested the wisdom of experts

15. Why are social networks interesting? Popular way to connect – Estimated 1.32B users online each day – Average American spends 40 minutes/day on the site Changing the flow of information – Formerly few ``writers’’ many ``readers’’ online – Now anyone can write! – What does this mean for Internet traffic? Useful in times of disaster 15

16. Social networks: Interdisicplinary Field social network analysis is an interdisciplinary social science; – Sociologists, computer scientists, physicists and mathematicians have made large contributions to understanding networks in general (as graphs) and thus contributed to an understanding of social networks [Social network analysis] is grounded in the observation that social actors [i.e., people] are interdependent and that the links [i.e., relationships] among them have important consequences for every individual [and for all of the individuals together].... [Relationships] provide individuals with opportunities and, at the same time, potential constraints on their behavior.... Social network analysis involves theorizing, model building and empirical research focused on uncovering the patterning of links among actors. It is concerned also with uncovering the antecedents and consequences of recurrent patterns. Linton C. Freeman

17. Social Network Examples Effects of urbanization on individual well- being World political and economic system Community elite decision-making Social support, Group problem solving Diffusion and adoption of innovations Belief systems, Social influence Markets, Sociology of science Exchange and power Email, Instant messaging, Newsgroups Co-authorship, Citation, Co-citation SocNet software, Friendster Blogs and diaries, Blog quotes and links

18. Social Networks Basic Questions Balance: important in exchange networks – In a two-person network (dyad), exchange of goods, services and cash should be balanced. – More generally, exchanges of “favors” or “support” are likely to be quite balanced. Role: what role does the actor perform in the network? – Role is defined in terms of Actors’ neighborhoods. – The neighborhood is the set of ties and actors connected directly to the current actor. – Actors with similar or identical neighborhoods are assigned the same role. Paradigm: interchangability. Actors with the same role are interchangable in the network.

19. Social Networks Basic Questions Prestige: How important is the actor in the network? – Related notions are status and centrality. Centrality reifies the notion of “peripheral vs. central participation” from communities of practice. – Key notions of centrality were developed in the 1970’s, e.g. “eigenvalue centrality” by Bonacich. Most of these measures were rediscovered as quality measures for web pages: – Indegree – Pagerank = eigenvalue centrality – HITS ?= two-mode eigenvalue centrality

20. How are links distributed 20 Mislove et al. 2007

21. Broadcasters News outlets, radio stations No reason to follow anyone Post playlists, headlines 13 User relationships on Twitter Mislove et al. 2007

22. Acquaintances Similar number of followers and following Along the diagonal Green portion is top 1-percentile of tweeters 14 User relationships on Twitter Mislove et al. 2007

23. Miscreants? Some people follow many users (programmatically) Hoping some will follow them back Spam, widgets, celebrities (at top) 15 User relationships on Twitter Mislove et al. 2007

24. On User Arrival - MySpace Public users What does u ser ID say about account creation time? Plot user ID vs. last login of that user for all our users Private users Torkjazi et al 2009

25. On User Arrival - MySpace 32% of public and 18% of private users are tourists Discovery of “tourists” enables accurate estimation of user account creation time based on their associated user ID Tourists “Clean edge” = users whose last login is shortly after their account creation time = “MySpace tourists” Torkjazi et al 2009

26. On User Departure - MySpace More public and private profiles in the first half of ID space More invalid profiles in the second half of ID space  Users joining the system earlier have been more likely to keep their accounts than newer users Are newer users more likely to leave than older ones? Torkjazi et al 2009

27. MySpace Life Cycle Slow-down in the growth rate of MySpace is related to emergence of Facebook Informal evidence (Alexa.com): Daily accesses to Facebook surpassed that of MySpace, at around April 2008 Possible reasons behind MySpace’s decline? Torkjazi et al 2009

28. Categories of pages 28 Schneider et al 2009

29. Session Characteristics 29 Schneider et al 2009

30. HTTP Traces Schneider et al 2009

31. Action popularity 31 Schneider et al 2009

32. Feature sequences 32 Schneider et al 2009

33. Types and Amounts of Info. Disclosed Gross et al 2005

34. Picture Posting Pattern 34 Erdin et al 2014

35. Video Posting Pattern 35 Erdin et al 2014

36. Non-Multimedia Post Frequency 36 Erdin et al 2014

37. Multimedia Data to Download As the time between logins increases, the total amount of data the user might download from friends increases. In extreme cases, it is observed 1GB of data when the user has not logged in for about a day. 37 Erdin et al 2014

38. OSNs: Wrap up Many different types of OSNs – Photos, video, profile-based Some extremely popular source of much Internet traffic – Facebook, YouTube New ones emerging – Instagram, snapchat Old ones fading – MySpace, Friendster Studying their properties can inform how we build networks and systems to support them! 38