Dive into the world of multivariable functions in this comprehensive lecture on Calculus 3. Explore the fundamental concepts of domain, sketching, and level curves as you begin your journey into multivariable calculus. Learn how to determine the domain of multivariable functions, master the techniques for sketching both domains and functions, and gain proficiency in finding level curves and creating contour plots. Through detailed explanations and practical examples, develop a solid foundation for working with functions of multiple variables, setting the stage for more advanced topics in multivariable calculus.