web services intermediaries

For the applications i worked on, it's only client / server - request /
response, one - one communication. But when i read SOAP specification, it
may have many intermediaries between the web service client and server

Here is my question -

1 -- Does Aixs support intermediaries and what is intermediaries used for?

2 -- Does use of intermediaries happen often in the real world industry?

3 -- What are example of intermediaries and use of it?

4 -- Are those intermediaries just another SOAP engine (e.g. axis) sit on
aother Computer / Host?

5 -- i also heard intermediaries modify the SOAP request / response too why
they need to do so?

6 -- i saw alot web service at www.xmethods.net they are all one - one -->
request / response, did all the web services there ever use intermediaries?
am i sending request to intermediaries or Ultimate soap receiver? Usually it
will have 1 request, and then response XML when i click on "Try It" there.