  Twenty-seven years ago, one of the biggest societal changes in human history
began slowly when the technical foundations for the World Wide Web were defined
by Tim Berners-Lee. Ever since, the Web has grown exponentially, reaching far
beyond its original technical foundations and deeply affecting the world today
- and even more so the society of the future. We have seen that the Web can
influence the realization of human rights and even the pursuit of happiness.
The Web provides an infrastructure to help us to learn, to work, to communicate
with loved ones, and to provide entertainment. However, it also creates an
environment affected by the digital divide between those who have and those who
do not have access. Additionally, the Web provides challenges we must
understand if we are to find a viable balance between data ownership and
privacy protection, between over-whelming surveillance and the prevention of
terrorism. For the Web to succeed, we need to understand its societal
challenges including increased crime, the impact of social platforms and
socio-economic discrimination, and we must work towards fairness, social
inclusion, and open governance.
  Ten Yars ago, the field of Web Science was created to explore the science
underlying the Web from a socio-technical perspective including its
mathematical properties, engineering principles, and social impacts. Ten years
later, we are learning much as the interdisciplinary endeavor to understand the
Web's global information space continues to grow.
  In this article we want to elicit the major lessons we have learned through
Web Science and make some cautious predictions of what to expect next.
