This is a term that refers to SEO tactics that are neither white hat SEO or black hat SEO, but include tactics that use elements of both. In other words, they are tactics that don’t violate the guidelines established by Google or Yahoo because the way in which SEO is being implemented in unclear. An example that relates from the world of accounting would be taking a tax deduction for an expense that is not expressly permitted or prohibited by tax law. To put it into SEO terms, a fantastic explanation of this type of SEO can be found on website “WordStream”.