IAM policies grant access using action strings like s3:GetObject or dynamodb:PutItem, but it is not always obvious from the name alone exactly what an action does. IAM Action Glossary is a searchable reference of common AWS IAM actions, each with the service it belongs to and a short, plain-English description of what it actually does.
This is deliberately a curated subset, not an attempt at AWS’s full action catalog. AWS documents thousands of individual actions across 300+ services, each with precise semantics (some actions, for example, only affect metadata, while similarly-named ones affect data). This glossary covers roughly 70 representative, commonly used actions across about a dozen widely used services — enough to be useful for reading and writing everyday policies, without pretending to be exhaustive or authoritative.
For the complete, authoritative list of actions (and their associated resource types and condition keys) for any AWS service, see that service’s page in AWS’s official Service Authorization Reference.