Staging
also: staging environment, staging server
A private copy of your app set up to match production closely. You test changes there before real users see them.
A pre-production environment configured as close to production as practical, with similar settings, services and realistic (but usually not real) data. It's used for final checks and demos before release.
Staging is the dress rehearsal: same stage, same costumes, same lights, but the seats are empty. You find the problems before opening night.
Some problems only show up in a setup that looks like production. Asking your agent to deploy to staging first catches them without putting real users at risk.
I've deployed the change to staging. Can you test a full checkout there before I promote it to production?
Deploy this to staging only. I'll check it on my phone before we release it to production.
Thinking staging and the development environment are the same. Development is your personal workspace. Staging is a shared copy built to look like production.