# Glossary

- **Admission**: Whether an item is allowed into cache at all.
- **Eviction**: Which resident item to remove when space is needed.
- **Recency**: How recently an item was accessed.
- **Frequency**: How often an item was accessed.
- **Scan pollution**: One-time accesses evicting genuinely hot items.
- **Ghost entries**: Metadata for recently evicted items to improve decisions.
- **Hot set**: The small subset of keys responsible for most accesses.
- **Hit rate**: Fraction of requests served by the cache.
