This article is the first in a series of two articles about the history of signature-based detections, and how the methodology has evolved to identify different types of cybersecurity threats. The core concepts still lie at the heart of all modern detection systems and will continue to be integral for the foreseeable future. As signature systems have evolved, they have become capable of detecting and classifying a broader range of threats. New machine learning algorithms are paving the way to a new signature class capable of economically scaling to scale to the threat scale.”]