What is the definition of a staging environment when developing web applications?

Question

When developing a web application for others, multiple environments for testing are a good idea. However, different development teams have different definitions for the meaning

Answer 1

"What properties would be appropriate when defining a staging environment?"

Technology stack must be the same. Indeed, you should be able to simply clone staging to rebuild production.

"Does the web server have to be on a separate physical machine than the database?"

For staging? Not necessarily. If your configuration management is rock solid then you'll have all the necessary config. parameters in staging and correctly fix them when moving to production.

If your CM is not rock solid, you'll need staging to have the same physical architecture as production so you can make configuration changes.

"Does the database have to be exactly identical to the production database?"

Depends on the use case. If you're upgrading the database, then they can't be identical.

If you're not upgrading the database, they will be identical.

"Can the staging environment go down for maintenance?"

Why not?

"Can the staging environment be used to test out new features (ie. a beta env)?"

It has to be used for this. How else do you do an upgrade?