Paul's Online Math Notes
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Free calculus notes from Lamar University covering the definition of a limit, one-sided limits, limit laws, infinite limits and continuity, each with fully worked examples and practice problems so you can evaluate limits by hand confidently.
More resources on Limits
Wolfram MathWorld
MathWorld is an online mathematics encyclopedia from Wolfram Research offering detailed, browsable articles on topics across the math spectrum, including algebra, geometry, calculus, and number theory. Each entry includes definitions, theorems, formulas, diagrams, worked examples, and links to further reading.
Jiří Lebl's Real Analysis Book (Free PDF)
Open-source undergraduate analysis textbook, free as PDF and used in university courses. Builds sequences, limits and continuity from the completeness of the reals with full proofs and exercises, so a reader can work epsilon-delta arguments unaided.
ProofWiki: Real Analysis
Category page on ProofWiki indexing definitions and worked proofs across real analysis, including limits of sequences and functions. Each statement links to its full proof and dependencies, useful for checking an argument you half-remember.
Introduction to Real Analysis
Learn real analysis fundamentals! This course, by William F. Trench, covers limits and essential concepts.
Real Analysis (MIT 18.100A)
Rigorous foundations of calculus: real numbers, convergence of sequences and series, continuity, differentiability, the Riemann integral, sequences and series of functions, uniform convergence and interchange of limits. Includes 25 lecture videos, notes, problem sets and exams, and teaches how to read and construct proofs.
Brilliant.org Limits
Interactive lessons on Brilliant covering limits, indeterminate forms and continuity through guided problems rather than lectures. Builds intuition for what a limit means before formal epsilon-delta work; most of the platform sits behind a paid subscription.