**2. Applications of REE**

Rare earth elements are applied in many different fields (**Figure 2**). They are used in mature industries such as catalysts, glass production, and metallurgy. However, they play an increasingly important role in the applications of high technology, which include batteries, ceramics, and permanent magnets. In the case of mature markets, elements such as lanthanum and cerium are most often used, in contrast to high-technologies, where dysprosium, neodymium, and praseodymium are used [7]. Permanent magnets production is the largest and most important end use of REE, accounting for over 29% of the total consumption of these elements in 2020 [5]. The main uses of rare earth elements are presented in **Table 1**. Above mentioned applications, there are still areas that use rare earth elements in new ways, such as nanotechnology, which can be employed e.g. in medicine. This chapter focuses primarily on the advanced applications of these elements in nanotechnologies as well as in the most important application in the world today, which are permanent magnets.


#### **Table 1.**

*Applications of REEs (after Refs. [7–10]).*
