There are a few cases where it's actually true depending on your host. For instance, if you use a Rails hosting provider, your image_tag, javascript_include_tag

There are a few cases where it's actually true depending on your host. For instance, if you use a Rails hosting provider, your image_tag, javascript_include_tag, and css_link_tag, you will get the benefit of far-future expires for free. This is not really specific to any particular Rails hosting provider; they all know that since Rails provides the cache-busting infrastructure, they can be aggressive about client-side caching.