Boost
Boost is a static page caching module that significantly improves Drupal site performance and scalability, particularly for sites with mostly anonymous visitors. It works by serving cached content directly, reducing the need for PHP processing and even allowing web servers to handle cached files without involving PHP. The module is highly configurable, offering advanced cache expiration logic and an integrated crawler to quickly regenerate expired content.
Boost provides static page caching for Drupal enabling a very significant performance and scalability boost for sites that receive mostly anonymous traffic. When there is no problem with your file system performance it is a good solution for shared hosting.
Since Drupal 8+ Version of this module Boost can serve cached content from files directly via RequestEvent independent from the used webserver. But it is still a good idea to use the webserver for serving static files. In this case there is even no PHP involved to serve content and get the maximal boost.
D8+ Version does not have a configuration helper , see Documentation about webserver (nginx and apache) configuration.
On D7 Module Apache is fully supported, with Nginx, Lighttpd and IIS 7 semi-supported. Boost will cache & gzip compress html, xml, ajax, css, & javascript. Boosts cache expiration logic is very advanced; it's fairly simple to have different cache lifetimes for different parts of your site. The built in crawler makes sure expired content is quickly regenerated for fast page loading.
Install
This is an advanced module and takes some extra effort to get it working correctly especially to configurea a webserver which is needed on D7 version wher boost requires cron & clean urls to be working; you will also have to edit your .htaccess and robots.txt files.
Boost Handbook for Drupal 7.x: features (included and missing/deprecated), requirements, credits. Installation instructions for Apache. Semi-supported: Instructions for nginx and IIS 7 on Windows Server 2008.
Boost Handbook for Drupal 6.x: features, requirements, credits, installation and settings, tips & tricks and testimonials. Also read the accompanying README.txt for installation and usage instructions. Don't forget to check for Boost errors & warnings on your status report page admin/reports/status
For the latest developments, see issues with the needs documentation tag.
Credits
4.7 Originally developed by Arto Bendiken
5.x Port by Alexander I. Grafov, developed & maintained by Mike Carper.
6.x Port by Ben Lavender, developed & maintained by Mike Carper. Since 2012, co-maintained by Mathieu Lu (bgm).
7.x Port by Mike Carper, co-developed and maintained by Mathieu Lu (bgm) and Philip Clarke.
8.x Version (rewritten) by Nicholas James, maintained and further development by Carsten Logemann
Boost Submodules
http://drupal.org/project/boost_captcha
http://drupal.org/project/expire
http://drupal.org/project/httprl
http://drupal.org/project/boost_expire
http://drupal.org/project/boost_custom_expire_rules
http://drupal.org/project/boost_cache_cleaner
Lists Of Other Caching Modules
http://groups.drupal.org/node/21897
http://drupal.org/node/326504