What is the stock market?

I'm looking for your deepest abstracted definition of the history and political nuance, the philosophical, the ethics, the evolved and historical meaning, and the meaningful impact it has had in evolving political structures and systems.

This is not ELI5, or a dumb question like "What is the stock market," /s... It is a question of dumb contexts like: what is it really under the surface, or what is it in your opinion, or what is it in principal, or what is it used for as a justification for other parts of society?