AWS Access Key ID

The AWS Access Key ID is an alphanumeric token distributed by Amazon that uniquely identifies a request sender. This ID must be included in every request using the AWSAccessKeyId parameter, as follows.

http://ecs.amazonaws.com/onca/xml?
Service=AWSECommerceService&
AWSAccessKeyId=[Your Access Key ID]&
Operation=ItemLookup&
ItemId=[An ASIN]

Note:

Before the introduction of the AWS Access Key ID, ECS used the Subscription ID for a similar purpose. If you have a Subscription ID, you can use its value with the AWSAccessKeyId parameter. You cannot, however, use an AWS Access Key ID with the SubscriptionId parameter.