How to bypass a browser's local cache. …
Modern browsers saves bandwidth and time by saving visited sites in their local cache (normally in your computer's memory and/or hard drive), so that they are downloaded only once. Sometimes this has the undesired and confusing result that a recent change appears to be ignored. Here's how to instruct browsers to temporarily bypass their cache.
Ctrl-F5 or Ctrl-Shift-R
12.00 and later
11.62 through 11.64
Ctrl-F5 or Shift-F5
As implied by the changelog for version 11.62, bypassing the cache is unreliable in previous versions. Upgrade to the latest stable version.
Although Wikipedia-specific, Bypass your cache gives good general information.
The online cache refresh test can be used to confirm that you are bypassing all caches, including intermediate caches operated by (for example) your ISP.