In the last couple of years, HTML comments became a popular way for web authors to communicate ideas discreetly to other web authors, who were the most likely folks to find these comments.
In order to stumble across these hidden remarks, the web user would have to view the source code for the web page. Aside from the naturally nosy, or those in the know about the existence of the comments, the most common reason for anyone to view the source code is to figure out how the page is designed in order to learn new web authoring techniques. Therefore, a savvy web author wishing to target a message only to other web-savvy individuals could hide extensive remarks inside HTML comments.
This technique was used most famously by the Gore Presidential campaign, which included a hidden message in the campaign web site. The message began, "Thanks for checking out our source code! ... The fact that you are peeking behind the scenes at our site means you can make an important difference to this Internet effort." From there, the message asked web designers to submit ideas for improving the campaign web site "in the spirit of the open source movement." Ironically, this clever attempt to build credibility among web professionals backfired. Gore was given some credit for the cleverness of the technique, but the internet community roundly criticized him for hypocrisy in claiming to support the open-source movement when, in fact, his entire web presence was built on closed-system technology developed by Microsoft. One Apache programmer likened the message to putting a "Buy American" bumper sticker on a Honda.
Besides the Gore campaign, other non-political web sites have found a use for hidden messages in their source code. Well-known web designer Jason Kottke runs a weblog, kottke.org, and has made a regular practice of inserting witty commentary appended to his own remarks. Some of his comments were originally meant only for his close friends, as inside jokes, but developed into an underground hit as Kottke’s cult-like following spread the word.
One of the most famous and widely imitated hidden-code tricks pulled by Kottke and a group of other web authors was to hide in their weblog entries as list of other weblogs, so that when authors of those site went ego-surfing, they would run across an entry which seemingly had no trace of the search term.
The rage seems to have subsided somewhat, but even though it’s now passé, web developers still view source code to learn new techniques, and this is one way for authors to target communication directly to that audience.