[maCCer]

do i need to do that for maintainance of Safari?
what is the function of clearing cache?Is that useful for keeping the OS health?
thx

[alphasubzero949]

Clearing the cache simply removes files saved for later visits to the same sites. On subsequent visits the browser compares the cache to what is on the web site. By doing so, it speeds up the page loading.

[TETENAL]

The cache saves files loaded from the Internet to the hard disk in case you encounter them later again so that they don't have to be downloaded again. For example when the "Post reply" and all the other images here at MacNN are cached, Safari doesn't have to download them all the time.

Clearing the cache can serve two purposes:

1)
Safari checks whether the cached file is still current, but maybe somehow an outdated file is stuck in the cache; clearing the cache forces Safari to download a current one.

2)
Clearing the cache can be a privacy measure. For example when you don't want your girl-friend or your boss to discover adult entertainment images in the cache.