I have worked with databases (or would that be databii?) of many flavors and for many, many years. And SQL is a language I am not afraid to approach. But by no means do I profess to be well versed in it.

I have a continuous struggle fully grasping the concept (and detailed implications) of the database join. My conceptual impression is that a JOIN represents a 'grafting' of two tables, linking them by a common field.
Is that close to correct?

Can someone offer a clear, descriptive explanation and some good analogy to help crystallize the concept?

I am calling on some of our Database experts, like @r937 ; to help me here.