While there are many options, we suggest WP Super Cache
This plugin generates static html files from your dynamic WordPress blog. After a html file is generated your web server will serve that file instead of processing the comparatively heavier and more expensive WordPress PHP scripts.
The static html files will be served to the vast majority of your users:
99% of your visitors will be served static html files. One cached file can be served thousands of times. Other visitors will be served custom cached files tailored to their visit. If they are logged in, or have left comments those details will be displayed and cached for them.
The plugin serves cached files in 3 ways (ranked by speed):
If you’re not comfortable with editing PHP files then use simple mode. It’s easy to set up and very fast.
Garbage collection is the act of cleaning up cache files that are out of date and stale. There’s no correct value for the expiry time but a good starting point is 1800 seconds.
Consider deleting the contents of the “Rejected User Agents” text box and allow search engines to cache files for you.
Preload as many posts as you can and enable “Preload Mode”. Garbage collection of old cached files will be disabled. If you don’t care about sidebar widgets updating often set the preload interval to 2880 minutes (2 days) so all your posts aren’t recached very often. When the preload occurs the cache files for the post being refreshed is deleted and then regenerated. Afterwards a garbage collection of all old files is performed to clean out stale cache files.
Even with preload mode enabled cached files will still be deleted when posts are modified or comments made.