The difference between Read Only and View Only permission

Today I came across a very good debate on View Only and Read Only permissions during a lunch break (in fact we all had a great FUN J)

Briefly speaking, View Only is one of the default permissions that can be directly assigned to groups or users in SharePoint sites; Read Only is a mode of viewing document.

They have some relations in SharePoint. View Only permission gives users the right to view pages, list items, and documents, but prevent any modification. That means, in item level, document can only be viewed in Read Only mode by the users with View Only permission.

A very good MS article on this

Microsoft Office SharePoint Server (MOSS): Permission levels and permissions

http://office.microsoft.com/en-us/sharepointserver/HA101001491033.aspx