Short answer
São Miguel is the largest island in the Azores archipelago, in the mid-Atlantic, and belongs to Portugal. It is home to Ponta Delgada, the largest city in the Azores and seat of the Regional Government's presidency, and has roughly 140,000 inhabitants—the most populous island in the Azores. For exact current figures, check the Portuguese statistics office (INE).
General information, not legal or tax advice. Rules and amounts change: confirm with official sources.