I believe it is safe to say that the highest volume of support calls in SharePoint Land is still around permissions. Ellen van Aken wrote a great blog series that showcases why this is such a tricky thing to manage in SharePoint.
Site Permissions Breaking Bad Episode 1
Site Permissions Breaking Bad Episode 2
[…] my earlier posts, so nicely combined by Veronique Palmer, I tried to visualize how SharePoint permissions work, and show and tell you what can go wrong when […]
Thank you for sharing. Awesome !!!