Glossary
Indexer
Infrastructure that watches a blockchain in real-time and writes its events into a queryable database — the backbone of any responsive dApp.
Querying a blockchain directly is slow: filtering historical logs across millions of blocks takes seconds at best. Indexers solve this by following the chain in real time and writing the events you care about into a normal database (Postgres, SQLite, Mongo).
The Graph is the largest decentralized indexing protocol; teams also run their own indexers via tools like Goldsky, Subsquid, Ponder, and Substreams. Any dApp that loads instantly is reading from an indexer, not from RPC.