HTML5 AppCache: Can somebody explain purpose of NETWORK section in manifest file?

I have gone through html5rocks, mozilla developer doc. Those definitions are very confusing. Can anybody explain this in simple terms ?

I am not sure why do we even need NETWORK section in appcache manifest file. I think it is as good as not having entry in CACHE section.

NETWORK Mozilla:

Files listed under the NETWORK: section header in the cache manifest file are white-listed resources that require a connection to the server. All requests to such resources bypass the cache, even if the user is offline. The wildcard character * can be used once. Most sites need *.

NETWORK HTML5Rocks:

Files listed in this section may come from the network if they aren't in the cache, otherwise the network isn't used, even if the user is online. You can white-list specific URLs here, or simply "", which allows all URLs. Most sites need "".