**1. Introduction**

The popularity of social media has significantly contributed to its massive use by different age groups of users. The overall rate of social penetration in 2020 reached a level of 49%. The highest rate was recorded in East Asian and North American countries at 71%. In the countries of Northern Europe, it reached a level of 67% [1]. The number of active users of social media in January 2022 reached 4.62 billion active users, which represents 58.4% of the world population. The most popular social media include Facebook (2910 million active users in January 2022), YouTube (2562 million active users in January 2022), WhatsApp (2000 million active users in January 2022 and Instagram (1478 million active users in January 2022). Recently, however, new social media, such as Tik-Tok (1000 million active users in January 2022) [2], are gaining more and more users.

The COVID-19 pandemic, and later the war in Ukraine, have largely highlighted the risks associated with the Internet and social media, especially in spreading fake

news and propaganda. Although both fake news and propaganda have been around for much longer than the events mentioned, it was during these crisis events that they began to spread more intensively than at any time before. This caused several negative aspects related to the use of social media and the need not only for a professional discussion about the possibilities of eliminating the spread of fake news, but also for the regulation of social media itself and the spread of content on the Internet.

On the other hand, the Internet and social media in times of crisis represent an important tool through which it is possible to inform the audience about current information, events, or measures. The use of social media thus presents opportunities as well as risks that must be known in order to be used as effectively as possible.

This chapter addresses the importance, role and status of social media during the COVID-19 pandemic and the war in Ukraine. It approximates the impact of these two crises (COVID-19 and the war in Ukraine) on the use of media in general, changes in social penetration and the way they are used. Special attention is paid to the change of paradigm and perception of social media by users and the phenomenon of the spread of fake news. In the context of the spread of fake news, it approximates the risks and opportunities associated with the use of social media, especially during a crisis. It focuses on the occurrence of fake news and the possibility of eliminating its spread, as well as current scientific knowledge about the impact of social media on critical thinking and the ability to identify fake news.
