**[Key Points of the Lecture]** There are various types of ion exchange resins, and it is necessary to select the appropriate one to remove ionic impurities from liquids. To do this, it is essential to understand the types and characteristics of ion exchange resins and choose one according to the intended use. The speaker has been engaged in the development of water treatment technologies using ion exchange resins for many years and will provide explanations including specific case studies. **[Knowledge to be Acquired]** 1. Basic knowledge about the types and characteristics of ion exchange resins. 2. Specific case studies of liquid treatment technologies using ion exchange resins. 3. Basic methods for evaluating ion exchange resins. **[Purpose of the Lecture]** Ion exchange resins are organic substances derived from petroleum products that have the ability to exchange ionic substances present in liquids with their own ions. This characteristic is widely used to produce "pure water and ultra-pure water" with minimal impurities. Additionally, they play a crucial role in the industry by removing harmful metals from wastewater, recovering rare precious metals, purifying food and pharmaceuticals, and serving catalytic purposes. This lecture will introduce the basic properties, types, applications, and evaluation methods of ion exchange resins, providing necessary information for their use.