For example, here is a high level generic step by step process that usually happens:

Spec written (some people seem to think this step is optional)
Developer develops code etc... Usually on a stand-alone, single server SharePoint environment. (I personally use a VPC for all development these days)
Developer packages code into an installer if you are lucky
Testing
Hand off to production people who go and install it on the server(s).

Depending on how your development team packaged these would depend on how much work you had to do to deploy them.