Custom Vision is a machine learning service by Azure AI that empowers users to build, train, and deploy custom models that can recognize specific images. It supports a range of image classification tasks, including object detection and image tagging. Users can upload their own labeled images, train their models, and evaluate performance, all from a simple web interface. This service is designed to be scalable and cost-effective, ensuring that users only pay for what they use, whether that be training hours or image storage.