Which AWS service or feature enables users to encrypt data at rest in Amazon S3?

Server-side encryption is an encryption option that Amazon S3 provides to encrypt data at rest in Amazon S3. With server-side encryption, Amazon S3 encrypts an object before saving it to disk in its data centers and decrypts it when you download the objects. You have three server-side encryption options to choose from: SSE-S3, SSE-C, and SSE-KMS. SSE-S3 uses keys that are managed by Amazon S3. SSE-C allows you to manage your own encryption keys. SSE-KMS uses keys that are managed by AWS Key Management Service (AWS KMS)5.