AWS is popular because it is highly scalable, secure, reliable, and cost-effective, making it suitable for businesses of all sizes looking to leverage cloud computing. Amazon S3 provides cloud-based object storage and allows businesses and individuals to store and retrieve large amounts of data quickly and easily from anywhere. S3 ensures data is secure and always available, and can be used for backup/recovery, hosting websites and media, and other applications requiring management of large data volumes without infrastructure maintenance.