Overview
When a cache line is kicked out (evicted) to make room for new data, it is placed in the victim cache. If the CPU needs that data again shortly after, it can retrieve it from the victim cache much faster than from the next level of the hierarchy.
Purpose
Reduces the penalty of 'conflict misses' in caches with low associativity, where two memory addresses compete for the same cache slot.
Modern Context
While standalone victim caches are less common today, the principle is often used in the interaction between L1 and L2 caches in exclusive cache designs.