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I've been reading a lot about cloud computing lately. Seems like everyone has an opinion. One of my favorites was an interesting comparison on the buzz (measured by Google Trends) that Cloud is getting compared to Utility, Grid, etc. Me personally... I'm still trying to grok what it all means. Seems to me that Clouds are Grids spiced with virtualization. Grids were great for serving up raw resources for clustered applications or like-minded apps that access the same storage or networking infrastructure. However, they are limited when a user wants to share the grid for dissimilar applications - e.g. ones with differing storage needs or HA needs. With a grid, you basically paid for the whole thing whether you need all the capability or not. This restricts the types of applications you can land on a grid. Now, add a bit of virtualization to the grid and the rigid boundaries seemingly disappear. Grid hardware can be partitioned using hypervisors so smaller apps can be placed on the grid. It also allows the grid to have a heterogeneous operating system policy, something you can do on a grid but only with great effort. This makes the grid more flexible - a Cloud? The issues with storage and network access are still there, and while server virtualization can help a bit here, the reality is that the physical connectivity is still an issue. What's next, an I/O Cloud? So to me, a Cloud is a Grid with virtualization. Is that your view? I'd be curious to see if someone has a good definition of a Cloud that can stand on its own.