  The forthcoming Fifth Generation (5G) era raises the expectation for
ubiquitous wireless connectivity to enhance human experiences in information
and knowledge sharing as well as in entertainment and social interactions. The
promising Visible Light Communications (VLC) lies in the intersection field of
optical and wireless communications, where substantial amount of new knowledge
has been generated by multi-faceted investigations ranging from the
understanding of optical communications and signal processing techniques to the
development of disruptive networking solutions and to the exploitation of joint
localisation and communications. Building on these new understandings and
exciting developments, this paper provides an overview on the three
inter-linked research strands of VLC, namely localisation, communications and
networking. Advanced recent research activities are comprehensively reviewed
and intriguing future research directions are actively discussed, along with
the identifications of a range of challenges, both for enhancing the
established applications and for stimulating the emerging applications.
