Mathematical Induction proves statements P(n) for all natural numbers n >= n0. Two steps: Base Case (verify P(n0)) and Inductive Step (assume P(k), prove P(k+1)). Think of it as a domino chain — the base case topples the first domino, the inductive step ensures each topples the next. Strong Induction assumes P(m) for ALL m <= k, then proves P(k+1). JEE rarely asks full induction proofs in Main (more common in Advanced), but tests understanding through MCQs: "which step fails," "what is proved in base case," etc. The most common application is proving summation formulas and divisibility statements. Always check that the inductive hypothesis is actually used in the proof.