  With the explosion of social media in the last few years, web pages nowadays
include different social network buttons where users can express if they
support or recommend content. Those social buttons are very visual and their
presentations, along with the counters, mark the importance of the social
network and the interest on the content. In this paper, we analyze the presence
of four types of social buttons (Facebook, Twitter, Google+1, and LinkedIn) in
a large collection of web pages that we tracked over a period of time. We
report on the distribution and counts along with some characteristics per
domain. Finally, we outline some research directions.
