### Untitled Document

At the heart of the Hypermedia protocol is the immutable data that is signed by authors and then distributed over [IPFS](/content/hm/z6Mko5npVz4Bx9Rf4vkRUf2swvb568SDbhLwStaha3HzgrLS/protocol/ipfs/index.html).

Aside from files/attachments, every [Data Blob](/content/data/data-blob/index.html) utilizes [IPLD DAG-CBOR](https://ipld.io/docs/codecs/known/dag-cbor/) format to produce structured IPFS blocks identified by [CID](https://docs.ipfs.tech/concepts/content-addressing/).

Here we introduce you to the [Signed Data Blob](/content/data/signed-data-blob/index.html) and all of the data it can produce. Then you can reference the [Protocol](/content/protocol/index.html) which builds on this knowledge to offer many different RPCs for exchanging the signed data and the interpreted results.

## Resources

All mutable data in the Hypermedia ecosystem is either a [Resource](/content/data/resource/index.html) or a [ChangeResource](/content/data/change-resource/index.html).

- [Document](/content/data/document/index.html)
- [Comment](/content/data/comment/index.html)
- [Capability](/content/data/capability/index.html)

## Data Blob Definitions

Each of these [Signed Data Blob](/content/data/signed-data-blob/index.html)s are objects with a "type" field that discriminates against the following types:

- [Ref](/content/data/ref/index.html) — A "commit" to a Document in a certain location
- [Change](/content/data/change/index.html) — Describes an update or creation of Document content
- [Comment](/content/data/comment/index.html) — A Resource that describes a comment
- [Capability](/content/data/capability/index.html) — A Resource that gives permission from one account to another
- [Contact](/content/data/contact/index.html) — The Resource that allows an Account to publicly annotate another Account with trust information
- [Profile](/content/data/profile/index.html) — Provides metadata for the Account

## All Definitions

### Profile

### Document

[1](/content/data/document/index.html)

### Capability

### ChangeResource

### Ref

### Change

### Signed Data Blob

### Data Blob

### Contact

### Comment

### Resource