# Object storage compared with a disk

> How object storage keeps files as objects in buckets, how that differs from a server's disk, and what each one suits.

Source: https://www.coritan.com/docs/learn/object-storage/

A server's *disk* works like the drive in your computer: programs open files, change a few bytes in the middle and save them, many times a second. *Object storage* keeps whole files, called *objects*, in containers called *buckets*, and programs reach them over the internet. You upload, download or delete one whole object at a time.

## How the two differ

| | A server's disk | Object storage |
| --- | --- | --- |
| Who can reach it | The server it belongs to | Any program with an access key, from anywhere, over HTTPS |
| How files change | Any part of a file, at any time | A whole object at a time: an upload replaces it |
| Folders | Real folders | Names with `/` in them, shown as folders |
| Size | Fixed by the server's plan | Grows as you store more |
| Suits | The operating system, databases and running software | Backups, media, logs, build output and files to share |

## Buckets, objects and access keys

*Bucket*
: Holds objects. On Coritan, every bucket is private, lives in one region, and has a name that starts with your account's namespace, such as `u7-assets` ([Create and delete buckets](/docs/object-storage/buckets/)).

*Object*
: One file, stored under its full name, called its *key*, such as `photos/2026/beach.jpg` ([Upload, download and delete objects](/docs/object-storage/objects/)).

*Access key*
: Lets a program sign in. It has an ID and a secret, can read only or read and write, and works on one bucket or on every bucket on your account ([Create and revoke access keys](/docs/object-storage/access-keys/)).

## The S3 API

Programs talk to object storage through the *S3 API*, a way of asking for objects that Amazon S3 made standard. Coritan's Object Storage speaks it, so backup tools, rclone, the AWS CLI and S3 code libraries work with it once you give them the region's endpoint and an access key ([Connect an S3 client](/docs/object-storage/connect-an-s3-client/)). You can also upload and download files in the dashboard, before you create any key.

## What it costs

An Object Storage service includes a storage allowance, set by its plan, and charges a rate per GB-month for what your buckets hold above it ([How Object Storage is billed](/docs/object-storage/usage-and-billing/)).

## Next steps

- [Store files and backups](/docs/get-started/store-files-and-backups/)
- [Order Object Storage](/docs/object-storage/order-object-storage/)
- [Connect an S3 client](/docs/object-storage/connect-an-s3-client/)
- The [Object Storage](https://www.coritan.com/storage/object-storage) product page on coritan.com