Who can run the Flow and how

There are various concepts related to who can run the Flow and how, what kind of permission is required to run a Flow, and what happens when an organization wants to open a Flow for external users or unauthenticated access? To see the Flow detail page, users must have View Setup and Configuration system permission; the users that have the Manage Force.com Flow system permission can open, create, delete, activate, deactivate, or delete Flows.

Debugging insufficient privileges on the custom button/link

A business scenario: Helina Jolly is working as a system administrator in Universal Container. She developed a Flow, that is, Create Leads, in Chapter 3, Manipulating Records in Visual Workflow (under the Hands on 1 – creating leads and Hands on 2 – adding leads to a campaign sections), and embedded it into the custom button. She has received several e-mails from users saying that they are getting Insufficient Privileges Errors when they click on the Create Lead button...