At some point, as a company grows rapidly, it becomes impossible to intuitively know its customers and decide which ones to focus on. Intercom faced this challenge in 2017 when its business grew to over 300 people, making communication between colleagues complex and fracturing the shared notion of the customer they once took for granted. To understand their customers better, Intercom relied on various frameworks, including the Jobs-to-be-Done framework, product sense, research insights, sales input, and a belief that their customers were companies like them. However, this approach was no longer useful as the company's customer base became more diverse, with B2C businesses, small businesses, and large enterprises, along with customers in different places and industries. Intercom needed a new way to understand its customer base in a structured, shared manner, which led them to explore customer segmentation. Segmentation is the process of grouping customers together based on common characteristics, such as demographic, geographic, behavioral, psychographic, or customer journey-based segments. By segmenting customers, businesses can identify profitable customers, develop customer loyalty, and refine their segments over time. However, segmentation should not be used as a substitute for strategy or planning, nor can it incorporate all strategic considerations, including changes to product pricing and packaging. Intercom's experience with customer segmentation has shown that it is necessary for growing businesses to know their customers and market, and share this understanding across teams. The company has benefited from segmentation in several ways, including describing types of customers in a common way across go-to-market, product, and engineering, understanding its most and least engaged customers at a granular level, surfacing promising or untapped business opportunities, enabling tactical decisions with a holistic view of customers, informing marketing strategy, assessing progress on marketing strategy, and driving adoption across teams. To implement customer segmentation effectively, businesses should align on problems and principles, create their segments, and drive internal adoption. This involves gathering data about customers, selecting variables to segment by, deciding on an approach to segmentation, validating the model, and sharing it with relevant teams. Ultimately, customer segmentation is a cross-functional endeavor that requires buy-in from all teams involved.