Microplastics are a consequence of the extensive use of plastics and the failure of managing their proper disposal. We know already that microplastics are found everywhere, but we still need to be sure if it is or it will be harmful to nature and how to deal with the problem. In this seminar, we will discuss the anthropogenic sources of microplastics and their geological fate, the role of the polymer degradation in their environmental impact, and the challenges posed by nanoplastics regarding monitoring and consequences.