Short answers, pulled from the story.
Charles Louis de Secondat baron de La Brède et de Montesquieu was born on the 18th of January 1689 at the Château de la Brède in southwest France. His birthplace was a stone fortress that became the cradle of his revolutionary ideas.
Montesquieu introduced the theory of the separation of powers in The Spirit of Law published in 1748. He argued that government should be structured with three distinct branches: the executive, the legislative, and the judicial, to ensure no man need be afraid of another.
Montesquieu influenced the American founders most notably James Madison of Virginia through his ideas on the separation of powers. His work became the most frequently quoted authority on government and politics in colonial pre-revolutionary British America, cited more by the American founders than any source except for the Bible.
Montesquieu developed the concept of climate theory and environmental determinism which proposed that climate and geography significantly influence the character of individuals and the formation of laws. He argued that cold climates enhanced strength and vigor while hot climates fostered sensitivity and emotional volatility.
The Catholic Church placed The Spirit of Law on the Index of Prohibited Books in 1751. This action followed a denunciation from the Sorbonne and marked a significant controversy surrounding Montesquieu's work despite its praise elsewhere in Europe.
Montesquieu died from a fever on the 10th of February 1755 after visiting Paris at the end of 1754. He was buried in the Église Saint-Sulpice in Paris.