**Abstract**

The popularity of social media has significantly contributed to its widespread use by different age groups of users, including children and seniors. In the online environment, especially on social media, users can encounter many threats, mainly fake news and disinformation. Although fake news and disinformation have been around for a long time in the Internet environment, the COVID-19 pandemic and the war in Ukraine, as well as other crises, have highlighted the dangers of their spread through the Internet, especially on social media, their impact on individuals, on the economy, and on society. This chapter discussed the main risks, but also the opportunities provided by social media during the last crises. It brings closer the change in media behavior and the use of social media during COVID-19 and the military conflict in Ukraine, the shift of paradigm in using social media, as well as the possible methods to fight disinformation.

**Keywords:** COVID-19, disinformation, fake news, media, social media, Ukraine
