By now it is conventional wisdom to say that there was an IBM Era of computing, then a Microsoft Era, and now we are in the Google Era. In this post, I will explain why Microsoft was not the 'next IBM' and why Google is not the 'next Microsoft' - there are significant qualitative differences among them, quite apart from their status as the dominant, era-defining players. Understanding that qualitative difference is crucial for third party vendors, like Zoho, to thrive. I was reminded of this because of the IBM/Google partnership unveiled last week. As an aside, I have coined a kind of Moore s Law on these computing eras.