1.4 Storage

S3 (Simple Storage Service): it is kind of virtual disk in the could where you can store objects. The objects here means files. It is not for installing databases or applications. If you want to do that, you need block based storage. S3 is object-based storage. Example: Dropbox.

Glacier: it is a place in which you archive your files from S3 off. If you don't need instant access to your file, for example you can wait for 4 or 5 hours, you can store it in Glacier, which play a role of archive. It is extremely low cost.

EFS (Elastic File System): it is file-based storage, you can install database or applications here and you can share it with multiple virtual machines.

Storage Gateway: it is a way of connecting out S3 to your own data center or to your headquarters. It is normally also a virtual machine on-premises or on VPC.

EBS (Elastic Block Storage): it is block-based storage, so you can install database or applications on it. It is just virtual disks that can be attached to your EC2 instance, so we don't consider it as a storage service of AWS.