What is the definition of Software as a Service?

If you go to www.microsoft.com/saas you will end up with the definition: “Software deployed as a Service and accessed using Internet technologies”. To me this is very broad probably too broad. Unfortunately I don’t have anything clearer and more precise than this.

From the talks with the parties involved and from the experience that I have with hosters around Europe I want to add some bullet points that appeared to me as very important and critical for SaaS in the scenario where Hoster and ISV become partners.