Social media platforms create rich social structures, expand users' boundaries of social networks and revolutionize traditional forms of communications, social interactions and social relationships. These platforms not only facilitate the creation and sharing of news and information, but they also drive various kinds of businesses models, processes and operations, knowledge sharing, marketing strategies for brand management and socio-political discourses essential for healthy and democratic functions. As such, social media has greater implications on organizations and society brought about by individuals' social media usage patterns, and therefore, calls for further investigations. The main objective of this dissertation is to explore and offer insights into such social media usage and information sharing behaviors via data driven examination of various theories. This dissertation involves three studies that focus on factors that explain individuals' three different social media usage behaviors. Essay 1 investigates individuals' perceived importance of online affiliation, self-esteem, self-regulation and risk-benefit structure as antecedents of users' geo-tagging behavior on social media. Essay 2 examines the role of online news quality, source credibility, individuals' perception towards online civic engagement, attitude towards news sharing and social influences to understand users' news sharing behavior on social media platforms. Essay 3 seeks to examine the individuals' information verification behavior on social media through the lens of individuals' fake news awareness, perceived cost of information verification, trust in social media and truth-seeking.

This work describes the problem of information credibility in state institutions with the help of using various methods (deduction, induction and synthesis). Work describes mainly theory but also some existing approaches in real work of this institutions. The work describes the problem beginning from collecting information, verifying information and information sources, related credibility, concepts, typologies and so on. Then, it describes the phenomenon of misinformation (or disinformation) and clarifies if this phenomenon is a part of real daily work of certain state institutions. Then in work is described the Ministry of Foreign Affairs of the Czech Republic and their approach to information (typology of information, resources, verifying information, actors which collect information). In addition, work presents such institution as the Office for Foreign Relations and Information, which is also a state institution and is a leading supplier of information to the MFA. Understanding the issue of such a sensitive topic in such closed institutions is based on publicly published sources. In work are also described methodologies of verifying information and procedures of risk management used in the situation of obtaining false information. At the same time, work contains a few of author's solutions for some parts of the work.