Let me expand.
If you need to store information related to a specific document (resource). You can put it in a TV and the specific value for that document will be saved. That TV can have a specific value for every different page. Suppose, for example, that you wanted a hit counter. There are several ways to do it, but one would be to create a TV called 'hits' and use a snippet or plugin to increment the value every time the page was visited. In the page template, you'd just put this:
Another use would be to record tags associated with each page for use in searching and sorting.
The @INHERIT TV is particularly useful because the value for the current page will be inherited from the nearest ancestor in the tree with the value set (if no value is set for the current page).
You could, for example, have a meta description HTML tag in the page template containing a snippet tag that used the 'description' field for the page but fell back to a 'Description' TV if the 'description' field was empty. If the Description TV default value was set to @INHERIT, you could set default descriptions in a container resource and all it's children would inherit that description, to be used if their 'description' fields were empty.
Of course you could do any of this with a snippet (though having tagged pages would be fairly challenging and probably inconvenient for the user). Using TVs is often much more convenient than doing it with a snippet. That said, if things get complex, the snippet version will often be faster.
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