How, what, when and why SOA?

After taking part in a recent discussion on SOA, I would like to say that SOA doesn't answer the questions How, What or even When in terms of use, but do answer the question Why.

How?
There is a misunderstanding that SOA has something to do with how people should implement their services or group them in types of service behaviors. SOA makes no difference between services implementing master-data, processes, use-cases, entities, identities, rules, or legacy adapters nor does it care. To SOA a service is just a service.

What?
SOA doesn't require a specific message-passing technology but Web Services is preferred for obvious reasons.

When?
SOA is not suitable in all situations - but that isn't up to SOA to decide. The answer here is dependent upon the how and the what described above.

Why?
SOA answer the why-question with - to achieve business agility. Not by how services are implemented or with what technology is used, but with service management - the things that happens between the 2 service endpoints during a call. Things like versioning, routing, filtering, virtualization, en/decryption, en/decoding, monitoring, transformation, logging, translation, billing, validation, etc - all packaged in a nice runtime governance tool.