A database client is a process that interacts with a database service.
We've seen one already: psql
Local access using psql
From postgres.eecs.tufts.edu, access the Postgres database service
running locally:
vm-postgres{jao}98:psql jao
psql (9.2.23)
Type "help" for help.
jao=#
jao: Connect to the jao database
As user jao (implied, since I am logged in as jao).