"Describe" a table in PostgreSQL

Query

SELECT column_name, data_type, is_nullable FROM information_schema.columns WHERE table_name = 'TABLE NAME HERE';

Example

SELECT column_name, data_type, is_nullable FROM information_schema.columns WHERE table_name = 'pg_database';
oid|oid|NO
datname|name|NO
datdba|oid|NO
encoding|integer|NO
datlocprovider|"char"|NO
datistemplate|boolean|NO
datallowconn|boolean|NO
datconnlimit|integer|NO
datfrozenxid|xid|NO
datminmxid|xid|NO
dattablespace|oid|NO
datcollate|text|NO
datctype|text|NO
daticulocale|text|YES
daticurules|text|YES
datcollversion|text|YES
datacl|ARRAY|YES