Reference: https://docs.servicenow.com/bundle/rome-platform-administration/page/administer/users-and- groups/concept/c_ImpersonateAUser.html

Explanation
Knowledge Management is the process that allows users to create, categorize, review, approve and browse important information in a centralized location that is shared by the entire organization1. Knowledge Management helps users to find relevant and accurate information quickly, reduce the need to rediscover knowledge, and improve the quality of service and customer satisfaction1.
References
Knowledge Management - ServiceNow1

Detailed Explanation:In ServiceNow, tables with names that start with u_ or x_ are Custom Tables. The prefix u_ is automatically assigned to custom tables created within a ServiceNow instance to distinguish them from core (standard) tables. Tables with the x_ prefix indicate they are custom tables associated with a scoped application, created within a ServiceNow application scope. Custom tables are crucial for extending ServiceNow's functionality and tailoring applications to meet specific business requirements. (Reference:
ServiceNow Documentation - Custom Tables and Table Naming Conventions)