Please explain what does development environment and production environment mean in the web?

Question

Capistrano

There are things that you immediately understand, but there are some things that you don’t understand even if you hit the wall.
Here there are such concepts as development, and production when developing.
What I know is that different dependencies, gems, plugins are stored there.
Can you explain what it means in development some gems, and others in production, or what are these environments for?
I would like you to clearly explain how a wise man to a child, so that he understands once and for all.

Answer 1

I can’t say for gems, but in dev builders, the assembly is usually with a watcher, unminified, with source maps. Prod - minified, without sourcemaps.
Because during development, debugging information is needed and the speed of generating assets is important. It's not needed for sale.

Answer 2

gem - files are instructions for building the project