In Oracle 11gR2, several key concepts are fundamental to understanding how the database operates and optimizes performance. These include Grid Computing, Real Application Clusters (RAC), Data Guard, and Automatic Storage Management (ASM). The Grid Computing concept allows for pooling resources across multiple machines, increasing scalability and availability. RAC enables multiple instances of Oracle to run on different servers while accessing the same database, providing high availability and load balancing. Data Guard ensures data protection by creating and maintaining standby databases. ASM simplifies storage management, reducing administrative overhead by automating tasks like disk allocation and performance optimization. Mastering these concepts is essential for optimizing Oracle 11gR2 deployments.