Amazon SageMaker is a service provided by Amazon Web Services (AWS) that enables users to build, train, and deploy machine learning models at scale. It offers a complete set of tools and workflows to simplify the machine learning process, including data preparation, model training, and model deployment. With SageMaker, users can access pre-built algorithms, use their own custom algorithms, and benefit from automatic model tuning. It also provides managed infrastructure for training and hosting models, making it easier for developers to implement machine learning solutions.