Calculus that makes the ideas click — limits through integrals, the span of AP Calculus and first-year college courses. Limits and continuity (one-sided limits, indeterminate forms, limits at infinity), the derivative as a rate and a slope, the rules (power, product, quotient, chain) and when each applies, implicit differentiation and related rates, applications (extrema, the Mean Value Theorem, optimization, motion), antiderivatives and the definite integral as accumulated change, the Fundamental Theorem of Calculus, substitution, area and average value, and differential-equation basics (slope fields, exponential growth and decay). Every explanation shows the reasoning, names the classic error (chain-rule forgetfulness, sign slips), and ends with a portable rule. Honest difficulty from one-step derivatives to multi-idea problems. Skill practice for courses and exams — independent, not affiliated with the College Board.