In a modern and big city, the security system is not a single layered single module system. Instead, it consists of many layers with autonomous subsystems which are capable of interfacing reciprocally in an efficient and coordinated way horizontally and vertically. The design of such indigenous subsystems and ensuring tight interaction between them taking into account high usability and resource utilization is not a simple task. In this regard, this article provides a comprehensive overview of the security systems in smart cities. We begin by introducing trends and key stakeholders in smart cities. Next, we provide examples of mass surveillance systems in developed countries like USA, UK, and China. Finally, we highlight some of the major challenges in complete realization of smart cities. The security aspects discussed in this study can be beneficial in designing future smart cities.

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Social media has a great influence on how information reaches us and how we form an opinion based on it. For many users, social media increases the variety of information and ensure its accessibility across different platforms. However, recent years have seen an exponential increase in the power of social media. Most often, the forwarding and sharing of journalistic articles serve the recommendation from the user's point of view, but recently, these platforms have been developed into an echo chamber to transport additional information or even a critical attitude. In addition, the uncontrolled influx of social media in different parts of the world favors phenomena such as fake news and social bots. These threaten the exchange of views sought by mutual understanding and sincerity that democratic societies need. Motivated by these observations, this article aims to paint a realistic picture of the impact of social media. To do so, we discuss the recent developments and social changes and provide analysis of the global impact of the connected audience. Next, we shed light on some of the opinion formulation procedures and its key enablers. Finally, we present an explanatory discussion on the Facebook algorithms and provide two case studies in the wake of recent global events.

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