Amazon Neptune is a fully managed graph database service provided by Amazon Web Services (AWS). It supports two popular graph models: Property Graph and RDF (Resource Description Framework). This allows users to build and query complex relationships between data points efficiently. Neptune is designed for high performance and scalability, making it suitable for applications like social networks, recommendation engines, and fraud detection. It automatically handles backups, software patching, and replication, ensuring that users can focus on their applications without worrying about database management tasks.