This paper will first, in Section 2, introduce the con
cepts of a smart city, big data, and applications of big data in a smart city. We will also investigate the current
definitions of these concepts available in the literature
and we will compare them. In Section 3 we will discuss
the benefits and opportunities of smart cities, big data,
and their applications and in Section 4 we will identify
the challenges of using big data for smart city applications and services. We will then move to offering an
overview of the general requirements to implement
smart city applications based on big data in Section 5. In
Section 6 we will discuss and illustrate some open issues
that may help other researchers start their research in
the field and in Section 7 we will conclude the paper.