Common psql meta-commands

\l List all databases in the system.
\c <database_name> Connect to the specified database.
\dn List all schemas in the current database.
\dt List all user-created tables in the current database.
\dtS List all system catalog tables.
\d+ <object_name> Show the definition of the specified database object (table, index, etc.).
\du List all users (roles) in the system.