A collection is a group of items that are related thematically. For example, all of the linens that go into a bedroom might be associated in a bedding linens collection.

The Collections response group returns all of the items in a collection. You can use ItemLookup, ItemSearch, ListLookup, and SimilarityLookup with the Collections response group to return collections. If, for example, ItemSearch returns four items and each of them are in a collection, the Collections response group returns the ASINs and titles of all the items in all four collections (even if some are duplicates), as shown in the following example.

<Collections>
  <Collection>
    <CollectionParent>
      <ASIN>B0006PLAOE</ASIN>
      <Title>Fieldcrest® Classic Bedding Collection GarnetIvory</Title>
    </CollectionParent>
    <CollectionItem>
      <ASIN>B00067IV8U</ASIN>
      <Title>Fieldcrest® Classic Solid Sheets Garnet</Title>     </CollectionItem>
    <CollectionItem>
      <ASIN>B000673NE2</ASIN>
      <Title>Fieldcrest® Classic Solid Pillowcases Set of 2 Garnet</Title>
    </CollectionItem>
    <CollectionItem>
      <ASIN>B00065WTJY</ASIN>
      <Title>Fieldcrest® Classic Dobby Pillowcases Set of 2 Garnet</Title>
    </CollectionItem>
  </Collection>
</Collections> 

This response snippet shows that there are four items in this collection: the collection name, Fieldcrest® Classic Bedding Collection GarnetIvory, and the items in the collection that are for sale: solid sheets, solid pillowcases, and Dobby pillowcases.

Product Advertising API does not offer a means of creating a collection. Collections are created internally by Amazon only.

Variations and Collections are Different

At first, collections might seem to be the same as variations but there are important differences. Items that are variations of one another are essentially the same item but in a slightly different form. For example, the variation of a blue, large shirt would be the same shirt in a different size or color. Items in a collection are fundamentally different from one another, for example, bed sheets and pillow cases could belong to the same collection, as shown in the following figure.