  With the rapid progress of recent years, techniques that generate and
manipulate multimedia content can now guarantee a very advanced level of
realism. The boundary between real and synthetic media has become very thin. On
the one hand, this opens the door to a series of exciting applications in
different fields such as creative arts, advertising, film production, video
games. On the other hand, it poses enormous security threats. Software packages
freely available on the web allow any individual, without special skills, to
create very realistic fake images and videos. So-called deepfakes can be used
to manipulate public opinion during elections, commit fraud, discredit or
blackmail people. Potential abuses are limited only by human imagination.
Therefore, there is an urgent need for automated tools capable of detecting
false multimedia content and avoiding the spread of dangerous false
information. This review paper aims to present an analysis of the methods for
visual media integrity verification, that is, the detection of manipulated
images and videos. Special emphasis will be placed on the emerging phenomenon
of deepfakes and, from the point of view of the forensic analyst, on modern
data-driven forensic methods. The analysis will help to highlight the limits of
current forensic tools, the most relevant issues, the upcoming challenges, and
suggest future directions for research.
