Here are the top 15 Most Popular Social Networking Sites as derived from our eBizMBA Rank which is a continually updated average of each website's Alexa Global Traffic Rank, and U.S. Traffic Rank from both Compete and Quantcast."*#*" Denotes an estimate for sites with limited data.

1 | Facebook
3 - eBizMBA Rank | 900,000,000 - Estimated Unique Monthly Visitors | 3 - Compete Rank | 3 - Quantcast Rank | 2 - Alexa Rank | February 1, 2015.
The Most Popular Social Networking Sites | eBizMBA
2 | Twitter
12 - eBizMBA Rank | 310,000,000 - Estimated Unique Monthly Visitors | 21 - Compete Rank | 8 - Quantcast Rank | 8 - Alexa Rank | February 1, 2015.
The Most Popular Social Networking Sites | eBizMBA
3 | LinkedIn
18 - eBizMBA Rank | 255,000,000 - Estimated Unique Monthly Visitors | 25 - Compete Rank | 19 - Quantcast Rank | 9 - Alexa Rank | February 1, 2015.
The Most Popular Social Networking Sites | eBizMBA
4 | Pinterest
22 - eBizMBA Rank | 250,000,000 - Estimated Unique Monthly Visitors | 27 - Compete Rank | 13 - Quantcast Rank | 26 - Alexa Rank | February 1, 2015.
The Most Popular Social Networking Sites | eBizMBA
5 | Google Plus+
30 - eBizMBA Rank | 120,000,000 - Estimated Unique Monthly Visitors | *32* - Compete Rank | *28* - Quantcast Rank | NA - Alexa Rank | February 1, 2015.
The Most Popular Social Networking Sites | eBizMBA
6 | Tumblr
34 - eBizMBA Rank | 110,000,000 - Estimated Unique Monthly Visitors | 55 - Compete Rank | *13* - Quantcast Rank | 34 - Alexa Rank | February 1, 2015.
The Most Popular Social Networking Sites | eBizMBA
7 | Instagram
77 - eBizMBA Rank | 100,000,000 - Estimated Unique Monthly Visitors | 49 - Compete Rank | 145 - Quantcast Rank | 36 - Alexa Rank | February 1, 2015.
The Most Popular Social Networking Sites | eBizMBA
8 | VK
97 - eBizMBA Rank | 80,000,000 - Estimated Unique Monthly Visitors | *150* - Compete Rank | *120* - Quantcast Rank | 21 - Alexa Rank | February 1, 2015.
The Most Popular Social Networking Sites | eBizMBA
9 | Flickr
123 - eBizMBA Rank | 65,000,000 - Estimated Unique Monthly Visitors | 138 - Compete Rank | 139 - Quantcast Rank | 91 - Alexa Rank | February 1, 2015.
The Most Popular Social Networking Sites | eBizMBA
10 | Vine
581 - eBizMBA Rank | 42,000,000 - Estimated Unique Monthly Visitors | 237 - Compete Rank | 335 - Quantcast Rank | 1,172 - Alexa Rank | February 1, 2015.
The Most Popular Social Networking Sites | eBizMBA
11 | Meetup
596 - eBizMBA Rank | 40,000,000 - Estimated Unique Monthly Visitors | 791 - Compete Rank | 701 - Quantcast Rank | 296 - Alexa Rank | February 1, 2015.
The Most Popular Social Networking Sites | eBizMBA
12 | Tagged
702 - eBizMBA Rank | 38,000,000 - Estimated Unique Monthly Visitors | 1,082 - Compete Rank | 615 - Quantcast Rank | 408 - Alexa Rank | February 1, 2015.
The Most Popular Social Networking Sites | eBizMBA
13 | Ask.fm
779 - eBizMBA Rank | 37,000,000 - Estimated Unique Monthly Visitors | 2,046 - Compete Rank | 113 - Quantcast Rank | 179 - Alexa Rank | February 1, 2015.
The Most Popular Social Networking Sites | eBizMBA
14 | MeetMe
1,457 - eBizMBA Rank | 15,500,000 - Estimated Unique Monthly Visitors | 1,407 - Compete Rank | 635 - Quantcast Rank | 2,328 - Alexa Rank | February 1, 2015.
The Most Popular Social Networking Sites | eBizMBA
15 | ClassMates
1,487 - eBizMBA Rank | 15,000,000 - Estimated Unique Monthly Visitors | 153 - Compete Rank | *285* - Quantcast Rank | 4,022 - Alexa Rank | February 1, 2015.
The Most Popular Social Networking Sites | eBizMBA