Boost is a module in Drupal that enables file based static page caching in Drupal. When an anonymous user visits a page for the first time in a Boost-enabled Drupal site, the page will get stored as a static html file in a cache folder. When the next anonymous user visits the same page the htaccess rules created by Boost will serve the static file cached in the cache folder instead of bootstrapping drupal for generating the page. This saves a lot of processor usage and would help even entry level hosting servers serve reasonably good volume of traffic. Here is how you can install and configure Boost in a Drupal 6 site.
Following steps should help you install boost module in drupal:
Step1: Download Boost Module : https://www.drupal.org/project/boost
Step2: Copy boost module folder to modules directory (sites/all/modules).
Step3: Enable boost module (Administer > Site building > Modules).
Step4: Ensure that Drupal's Clean URLs setting is enabled and working correctly( Administer > Site Configuration > Clean URLs).
Step5: Save the settings to install.
Step6: Take the settings page of boost module (Administer > Site configuration > Performance > Boost settings) Make sure that the Boost – Static page cache is set to Enabled and save the configuration.
Step7: Copy the custom rules from Boost .htaccess rules generation page to the Drupal .htaccess file. (Administer > Site configuration > Performance > Boost htaccess rules generation).
Step8: Paste it below the “# RewriteBase /” and above “# Rewrite URLs of the form 'x' to the form 'index.php?q=x'.” in the existing .htaccess file:
# RewriteBase / ------------ Paste the rules here ------------ #Rewrite URLs of the form 'x' to the form 'index.php?q=x'.
Step9: Run Status report and view your log entries to check to see if any errors related to the module configuration are being shown (Administer > Reports > Status report).