Feeds are a good way of following websites and reading them at one place (in a Reader). But there are two problems with following website content thru a feed.
1) Not all sections of a website have feeds; for instance several websites have posts feed, but no feed for the comments; and
2) Not all websites have feeds altogether; as they want you to visit the site to savour the content.
Then how to follow a website which either doesn’t provide a feed; or although has a feed for the main content, doesn’t have feeds for the content that you want to follow?
The solution is the newly introduced feature in Google Reader(if you don't use, then use it, by far the best). The feature lets you create a custom feed (in case of any of the above two scenarios described), so that you can track changes on the pages that don't have their own feed.
These custom feeds are specially useful if you want to be alerted whenever a specific page has been updated.
An example will make things clearer.
A real estate website, Zillow, http://www.zillow.com/ doesn’t provide feed at all. But you want to follow not only the main content of the site, but also other content too, like Advice, Directory, Mortgage etc.
If you want to follow Zillow (in general or main content), just paste or type http://www.zillow.com/ into Reader's "Add a subscription" field and click add. You’ll be shown a message informing about the non-existence of the feed. Allow Google Reader to make a feed for you--Click "create a feed". With this, you have successfully subscribed to Zillow thru a a Google-created feed.
In order to follow other sections like Advice, Directory, Mortgage etc, just go that page and do the same as described above.
In short, whatever link you’ll submit in the “Add a subscription” field of Google Reader; Google will create a customized feed for you, which you can easily follow.
How to follow a website which doesn’t provide a feed