Ever since the release of Google’s Web Accelerator tool, there have been many who follow the search engine industry questioning the purpose and the effects of prefetching.

For those who are unaware, prefetching is according to Mozilla:

a browser mechanism, which utilizes browser idle time to download or prefetch documents that the user might visit in the near future. A web page provides a set of prefetching hints to the browser, and after the browser is finished loading the page, it begins silently prefetching specified documents and stores them in its cache. When the user visits one of the prefetched documents, it can be served up quickly out of the browser’s cache.

Google preforms prefetching for searchers who use the Firefox browser. Firefox users who perform Google searches have the top listing of each query prefetched in order to, in Google’s words, speed up the web.

An article by John Battelle discussed the outcry against Google’s prefetching practice. The biggest complaint has to do with the fact that prefetching can skewer site log statistics, which measure who and when a user visited the site, among other things. Because of the method Google uses to prefetch data, site logs can show site hits where none occurred.

For a number of reasons, some consider this to be poor practice on Google’s part. Battelle’s article contains an excerpt from a post by privacy advocate Lauren Weinstein, which says:

Bottom line: Creating a situation where users are “automatically” accessing search-result sites without their having taken explicit actions to do so is very bad policy. This problem is not the fault of Google alone — the prefetching mechanism has been present in Mozilla-based browsers for quite some time.

Google’s defense of their prefetching methods lies in the fact that their actions comply with current web standards and they only prefetch the first search result. Google says they are doing so to speed up the web for their Firefox users and that they are only taking advantage of technology existing within the Firefox browser.

As Battelle’s article indicates, webmasters can always filter out prefetch requests and users can also turn the procedure off, which is explained by Mozilla:

Is there a preference to disable link prefetching?

Yes, there is a hidden preference that you can set to disable link prefetching. Add this line to your prefs.js file located in your Mozilla profile directory:

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Chris Richardson is a search engine writer and editor for Murdok. Visit Murdok for the latest search news.