Server log files are records of your site's activity. The log file data can offer you some valuable insights into how your users are using your Web site.
Your log files could reveal:
that some Web pages that are never visited; further investigation could reveal that links leading to those pages are broken
where in the secure ordering process do customers abandon the sale; modification of the offending page(s) could improve the checkout abandon rate
that one section of your site is much more popular than the rest; with this information, you may decide to concentrate and expand that section
There are plenty of log file analysis and reporting tools that can help you make sense of the data available in your log files.