An approval is a mechanism to block execution of a workflow request until the required approval is granted. Approvals can be configured for a folder or an application. A deployment of a project will require any approvals defined on its application or the nearest folder in the hierarchy to be approved. The need for an approval is determined by searching up the project navigation tree from the deploying application or project until an approval is found or the root folder is reached. Approvals are not additive and approvals set at lower levels in the hierarchy override higher level approvals. Approvals can be configured by environment at each level, providing the ultimate flexibility.

There are two types of approvals

See Also - Approve or Reject with Email Reply 

Approval Types