The Cloud Logging component that decides where each log entry goes. Sinks send logs matching a filter to log buckets, BigQuery, Cloud Storage, Pub/Sub, or other projects, and exclusion filters discard the ones you do not want to store.
On the ACE: an aggregated sink at the organization centralizes logs from every project, Pub/Sub sends them to an external SIEM, and exclusions cut the cost of logs nobody uses.
Log Router and sinks is a concept that can show up on the exam. Check the full guide to see it in context.