Functions are the main star of our course. Calculus isn't just about numbers: it's about relationships between things, and understanding how one thing changing affects something else. A function keeps track of these relationships.
The limit of a function is a main concept in this course. To understand limits in general, we'll first focus in on the specific case of the limit of a fraction, and then look at more complicated examples arising in trigonometry. We'll be using rules like "the limit of a sum is the sum of the limits" and "the limit of a product is the product of the limits."