What was progressivism? Was it a movement? A series of movements? A collective ideology?

What was progressivism? Was it a movement? A series of movements? A collective ideology? What was that ideology, if there was just one? Where was it most effective? How do you interpret the contradictions within progressivism? Can a single movement exist that includes subsets that are fundamentally in conflict with one another? Be specific about the individual strains of progressivism you are addressing, and consider how those fit together in this era.