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If you’ve been developing for the Web for any period of time, you’ll have seen new concepts and technologies come (and many of them go) thick and fast. Some, like Cascading Style Sheets (CSS), stick and change the way the Web works. Others, like Scalable Vector Graphics (SVG), may or may not have this same impact—only time will tell. Still others simply fade away, never living up to their initial promise.

New technologies often face a “chicken or egg” moment. No matter how much promise a technology has, it must be adopted and word of mouth about it must spread, or it will simply fade away, much like “push” technologies and Smell-O-Vision.

The history of HTML is convoluted. HTML began life as a simple, structural, semantic markup language for publishing scientific documents. As the popularity of the Web grew, more and more presentational aspects (elements like <font> and attributes like bgcolor) were added by browser developers (I’m looking at you, Netscape; what were you thinking with <blink>?), until HTML morphed into a mishmash of ad hoc “innovations” that strayed far from the original intent of its developer, Tim Berners-Lee.

By now I’m sure you’re itching to get your hands on some actual microformats. The previous chapters covered a lot of reasonably theoretical aspects of HTML that you’ll need to understand to really come to grips with microformats in practice. Now it’s time to get your hands dirty.

As you progress through the book, the microformats you encounter will become increasingly more complex. In the last chapter, you learned about link microformats, and their use of the rel and rev attributes of HTML. The chapter ended with a discussion of VoteLinks, which, unlike the previous formats you saw, allows multiple values on the rev attribute.

Google Maps, along with Yahoo Maps, Microsoft’s mapping products, and a significant number of smaller, dynamic mapping companies like Multimap and ZoomIn, coupled with increasingly inexpensive Global Positioning System (GPS) devices (now you can even get cameras that know where they are using GPS!), have all been part of the explosion of geographical and address data on the Web over the last couple of years. But standardized formats for marking up addresses or geographical locations using longitude and latitude have been missing from the equation. Each service typically has its own way of marking up data—for example, Google uses Keyhole Markup Language (KML), an XML-based format, while Yahoo uses GeoRSS, a variation on RSS. In the meantime, this lack of uniformity hasn’t stopped developers from adopting all kinds of conventions for marking up location-related data, such as visible geotags by Flickr users (you’ll see how Flickr now provides a way of geotagging using microformats later in the chapter).

Above all else, and despite the wishes of traditional media companies, the Web is a medium for two-way communication. Technology sites like Slashdot and Digg, and political sites like Daily Kos are as much about the discussion as they are about the articles. Rare is the site that does not prominently feature a Contact link on its home page. And with blogging in particular, the two-way conversation of trackbacks and comments are essential to the medium.

The rise of blogging demonstrated something that was always true about the Web, but that got somewhat lost in the feverish explosion of online sandwich delivery and multimillion- dollar sock puppets in the late 1990s web bubble: the Web is about people and their relationships. It’s about what we feel and believe, and it’s about conversations—online and in person.

So far, all the microformats presented in this book have been at what’s termed the specification stage. To reach this stage, according to the microformats process (which we’ll discuss in more detail in Chapter 13), a format “should be stable enough so that developers can pick it up and write to it.” Before a microformat reaches this stage, but is still sufficiently advanced in development, it is considered to be in draft stage.

Syndicated content , most commonly blog posts, has been one of the fastest growing kinds of content on the Web the last four or five years. Typically, the syndication is enabled not with HTML-based content, but with complementary formats, like RSS.