I now save a local archived/cached copy of nearly every page I link to because pages are routinely deleted, their content changed, missing the critical discussions posted by readers, or the host site no longer existing. Within a few days, nearly all traces of the old contentis replaced or removed from the caches at Google and other search engines. (I suspect that Google has everything archived for internal use, but that help me or someone reading my posts.)

There are several sites which attempt to archive the entire Web, retaining each revised version of a page seen by their web crawlers and thus able to derive a "snapshot" of a web site as it appeared on any given date. These efforts can be quite useful, but have their limits. First, content can appear and disappear between crawler visits to the site and never by archived; the links posted at DU are particularly vulnerable to this, whether to a rapidly changing news site or to an obscure site that is infrequently visited by the crawlers.

Second, our informal concept of "linking to a web page" is the key to defining a web on top of a net, implemented by specifying HTML and the http: protocols and network services and then creating new types of software, web servers and browsers. For many years, most web pages existed as simple text files containing HTML containing links to images and other web pages. The link/URL processing was trivial: Use DNS to convert the server name to IP address, connect to socket 80 at that IP, send a message to that socket requesting the URL, and receive in response from the server the corresponding HTML file. The response from the web serverwas the same whether you, I, or a web crawler had requested the page.

Today, the link/URL is barely more than a "hint" to the hosting web server about what and how it will respond and what vast chain of events will be triggered. Even in a simple case, the content and formating might depend on who requested the "page" and what the hosting site knows about them -- consider your login to DU and your profile and preferences, maybe what browser you are using, posts by other users, and who knows what else.

Reality is much worse, more complex, less reliable, manipulated in all directions by valid content providers, malware of all sorts, marketing and market manipulation promoting products, scams, candidates, political causes, grassroots and astroturf, criminals, despots, the good, the bad, and the ugly -- and each of these, in turn, under attack by opposing forces. A very Mad world of Spy vs Spy (vs Spy vs Spy ...).

So make sure you save a local copy of things you find important while you can and be sure to verify that the saved version actually contains the content. Many sites now manipulate the browser and its cache so that your attempt to save the "page" triggers a refresh of the page from the server and the refreshed version is missing the actual content, replaced with just a link back to the web site. If you view the saved file with the browser, it will display with the content (retrieved again) and appear ok. Be sure by unplugging from the network and checking again, maybe using some application that lets you see the saved HTML itself.

When really paranoid, I make printed copies and even capture and print screen captures of my display containing the critical information. This technique usually avoids alerting the web site or other parties of your interest in this particular information and avoids leaving easily-accessible history of your actions. (Assuming your computer is not completely compromised by keyloggers or other spyware. That is probably not a good assumption for most people using popular browsers and environments -- MS Windows, Mac, Linux, Unix -- not even FF on Linux in safe mode or with noscript, flashblock, and such. Take precautions where you can, but assume that these efforts are inadequate and still at risk.)

Stay sane inside insanity.

Sorry for the long warning note, but
They mustn't carry out their evil deeds.