In this chapter, we will explain patching concepts in EBS 12.2. We will provide the information about the components and utilities used in patching and shed light on the logic behind the patching methods. In addition, we will cover the usages and roles of the dual file system and edition-based redefinition in EBS 12.2 patching. Further, we will introduce the new patching cycle concept in EBS 12.2 as well as the patch phases used in the online patching concept and explain best practices for EBS 12.2 patching. Both application tier and database tier patching will be covered in this chapter.