The value entered in the "town" field is tacked on to the end of the CGI's URL like this:
When the form data (or "query data") is added to the end of the URL it is "URL encoded" so that the data can be used in a standard URL. The neat thing about URL encoding is that each different query to the CGI has a different URL. Those unique URLs can be used directly in links without any form being involved. For example, the URL above can be used to create a link to exactly the same CGI results:
<A HREF="../cgi-bin/mycgi.pl?town=West+Rochester">West Rochester</A>
which creates this link: West Rochester.