Cypher is the declarative query language for Neo4j, the world's leading graph database, and it keeps evolving with time. The language is constantly documented in a reference card that is updated for every new version of Neo4j. You can find the complete Cypher Ref Card online at https://neo4j.com/docs/cypher-refcard/current/.
The refcard is also available from the Neo4j browser, the third tab on the left of the screen ("Documents") has a Cypher Refcard link.
Although URL schemes changed between versions, like http://neo4j.com/docs/2.0/cypher-refcard/ for version 2.0 and http://neo4j.com/docs/cypher-refcard/3.1/ for version 3.1, older versions of the refcard are still available.