Amazon S3, or Amazon Simple Storage Service, is a cloud storage service provided by Amazon Web Services. It allows users to store and retrieve any amount of data from anywhere on the web. S3 is designed for durability, scalability, and security, making it suitable for a wide range of applications, from backup and archiving to hosting static websites. Users can organize their data in "buckets," which act as containers for storing files. S3 supports various data formats and offers features like versioning, lifecycle management, and access control. This flexibility makes it a popular choice for businesses and developers looking to manage their data efficiently.