In the world of marketing, understanding how different variables influence consumer behavior is key to designing effective advertising campaigns. One of the crucial concepts in this domain is the Advertising Response Curve (ARC), a function in marketing mix modeling that describes the relationship between advertising spend and the resulting consumer response. This article will delve into the intricacies of ARCs, detailing their function, significance, and how they intersect with critical elements such as saturation points. We will also investigate the impact ARCs have on Media Mix Optimization, specifically, the Return on Investment (ROI) , and shed light on the various industry-standard types of curves. Lastly, we will deep dive into the process of building an ARC.