Cache eviction policies are strategies used to determine which items to remove from a cache when it becomes full. These policies help maintain optimal performance by ensuring that frequently accessed data remains available while less important data is discarded. Common policies include Least Recently Used (LRU), which removes the least recently accessed items, and First In, First Out (FIFO), which removes the oldest items first. Choosing the right cache eviction policy depends on the specific use case and access patterns. For example, Least Frequently Used (LFU) targets items that are accessed less often, while Random Replacement removes items at random. Each policy has its advantages and trade-offs, impacting system efficiency and speed.