A Taylor series is the infinite-series version of a Taylor polynomial. Instead of stopping after finitely many terms, you continue forever:
When a=0, this is a Maclaurin series. These series represent functions locally as infinite polynomials, and for many important functions, the series converges to the function on a whole interval. In BC calculus, you often find these by recognizing a known series or by using derivatives at the center.
You should know the major standard Maclaurin series and be able to build others from them. The most important ones are for . Once you know those, you can often substitute expressions, multiply by constants, or shift variables to create new series. This is one of the most powerful parts of Unit 10 because it turns difficult functions into algebraic series you can manipulate term by term.