SharePoint Designer Workflows Process Identity

When a SharePoint Designer (SPD) workflow runs, it runs in the context of the workflow initiator. This is important to know if the initiator may not have permissions to everything that the workflow does.

See SharePoint Designer Workflows – what user identity?

SharePoint Designer 2010 introduces the new impersonation step. Please note that the impersonation step can be run only as the user who authors the workflow. The author of the workflow, most likely, is not the same as the identity of the SharePoint timer job.