Psql includes a built-in help command that is amazing.
With no arguments, it returns all the help:
app_development=# \h Available help: ABORT ALTER TABLESPACE CREATE FOREIGN TABLE ...
With a Postgres command as an argument, it returns a specific help:
app_development=# \h abort; Command: ABORT Description: abort the current transaction Syntax: ABORT [ WORK | TRANSACTION ]
And with an asterisk, it prints the full description for all the help commands.
Plus we get this nicety:
Note: To simplify typing, commands that consists of several words do not have to be quoted. Thus it is fine to type \help alter table.
Write better SQL in your REPL today!
h/t Jack Christensen