Dark Social is term coined in 2012 by Alexis Madrigal of the Atlantic Magazine and refers to website traffic that cannot be sourced or tracked through normal analytics.

More plainly stated, most web site owners are able to use products such as Google Analytics to determine the source of web traffic – for example if it was referred from Facebook, LinkedIn or other social networking site. It is assumed that all other sources of traffic were more or less direct, that is, someone knew the correct URL and typed in the correct URL directly.

The problem is that many of these “other sources” are not truly where the website URL was directly typed in, but instead is a link referral through email, texting or other non-trackable source. Many web masters claim that between 25 and 50 percent of their web traffic cannot be tracked to its source, and most believe that the situation will become worse not better.

Furthermore, although not mentioned extensively elsewhere, data collected for sentiment and web opinion analysis is never sourced from dark social sources – and a potentially critical amount of information is never analyzed. No one seems to be able to measure the magnitude of this problem.

The message is to be wary of conclusions drawn solely from standard analytics and sentiment analysis. It may be showing only part of the picture and may be biased along many dimensions.