From MozillaZine Knowledge Base
When a page is loaded, it can be cached so it doesn't need to be downloaded to be redisplayed. This preference controls whether to cache files retrieved by HTTP or HTTPS either in memory or on disk.
Possible values and their effects
Cache HTTP and HTTPS files. (Default)
Don't cache HTTP or HTTPS files.
First checked in
Has an effect in
- Netscape (all versions since 7.0)
- Mozilla Suite (all versions since 0.9.6)
- Phoenix (all versions)
- Firebird (all versions)
- Firefox (all versions)
- Thunderbird (all versions)
- Minimo (all versions)
- SeaMonkey (all versions)