# Collections

Collections are groups of [wearables](https://docs.decentraland.org/contributor/content/entity-types/wearables) and [emotes](https://docs.decentraland.org/contributor/content/entity-types/emotes) defined in the same off-chain namespace or on-chain contract.

They are not [entities](https://github.com/decentraland/docs/blob/main/contributor/entities.md) in and of themselves, but their individual items can be obtained from content servers normally using [pointers](https://github.com/decentraland/docs/blob/main/contributor/pointers.md).

### URNs and Pointers <a href="#pointers" id="pointers"></a>

Collections are identified using URNs, which are prefixes to their item URNs. There are 4 general types of URNs:

* `v1` collections with Foundation-approved content (deprecated).
* `v2` collections with community-approved content.
* `thirdparty` collections with items associated to NFTs outside Decentraland.
* `off-chain` collections, containing mostly default items for new avatars.

{% hint style="info" %}
Despite the fact that `v1` collections are deprecated and will not be created or updated anymore, they are still valid and their items can be used.
{% endhint %}

#### Version 1 and 2 Collections

Both the old `v1` and the current `v2` collection namespaces have URNs of the same form:

```
urn:decentraland:<blockchain>:<collections-version>:<contract-address>
```

For example:

```
# A collection in the deprecated v1 space:
urn:decentraland:mainnet:collections-v1:DCL Test Masks

# A collection in the v2 community-approved space:
urn:decentraland:matic:collections-v2:0x25a1d66891d44cdf7b8c45802489c1dea7aadf8b
```

If the `:<id>` segment is appended at the end, the URN becomes a [pointer](https://github.com/decentraland/docs/blob/main/contributor/pointers.md) to an item inside the collection. See [wearable pointers](https://docs.decentraland.org/contributor/entity-types/wearables#pointers) and [emote pointers](https://docs.decentraland.org/contributor/entity-types/emotes#pointers) for information on these.

#### Third-party Collections

Third-party collections, also known as [linked wearables](https://github.com/decentraland/docs/blob/main/contributor/wearables-and-emotes/wearables/linked-wearables.md), are different from regular wearables in that they are tied to existing NFTs outside Decentraland. They allow players to display NFTs from their personal set on their in-world avatars.

Their URNs look like this:

```
urn:decentraland:<blockchain>:collections-thirdparty:<third-party-id>:<collection-id>
```

You can find ample information about these in the [linked wearables](https://github.com/decentraland/docs/blob/main/contributor/wearables-and-emotes/wearables/linked-wearables.md) documentation for creators.

### Discovering Collections

Content servers can give you a list of all known collections, using the [`/lambdas/collections`](https://decentraland.github.io/catalyst-api-specs/#tag/Lambdas/operation/getCollections) endpoint.

The response will be an object with a `collections` property, containing an array of URNs and names. For example:

```json
{
  "collections": [
    {
      "id": "urn:decentraland:amoy:collections-v2:0xff5d4ebc6bc1ff7262cab42d3c693d953f4614d2",
      "name": "Winter clothes collection"
    },
    // ... many more
  ]
}
```