In the last couple of years, the adoption of microformats has helped make information on the Internet, such as contact information, machine readable. But still, microformats are not a revolutionary technology. They are an evolutionary use of standards-compliant Hypertext Markup Language (HTML).

At first glance, it may appear that microformats are only sanctioned classitis (the excessive use of classes and divs). These are usually added to provide hooks for cascading style sheets (CSS) styling. Microformats, using class and id attributes, provide additional meaning to semantic HTML markup. Allsop provides a working definition: “Semantic HTML is the use of the most appropriate HTML elements and attributes for the content we are marking up.” The only thing that the reader requires, in order follow along with the examples, is the Firefox 2 Web browser. Firefox has numerous extensions for developers, as well as extensions for displaying microformatted content.

Part 1 provides an introduction that explains what microformats are, and identifies some of the publishers of Web content. Microformats are based on the following principles: solve a specific problem; start as simply as possible; design for humans first, and machines second; reuse building blocks from widely adopted standards; be modular and embeddable; and enable and encourage decentralized development, content, and services. One of several advantages to using microformats is that they help enable published data to be aggregated and indexed. Using microformats, Web-based contact information can be accessed by desktop applications like Outlook, Mac OS X Address Book, and other software that uses the vCard standard.

Part 2 explains how to use microformats. It begins by addressing simple microformats and progresses to compound and complex microformats. According to Allsop, the Extensible HTML (XHTML) friends network (XFN) microformat is the original microformat. Its creators, Eric Meyer, Matt Mullenweg, and Tantek Çelik, observed that blogrolls are a list of various relationships. XFN is a way of expressing these relationships within HTML.

An online resource with authoritative information on microformats is microformats.org. This Web site is maintained by a community of microformat pioneers, including Çelik. Anyone with an interest in microformats is welcome to participate.

The hCard microformat is used to mark up contact information. It provides a semantic way of marking up people, organizations, and places. The hCard microformat is based on the vCard standard from the Internet Engineering Task Force (IETF) and is described as having an “electronic business card” format. This microformat incorporates two of the most important underlying principles: “solving a specific problem” and “reuse[ing] building blocks from widely adopted standards.” The hCard format includes fields for a formatted name, structured name (including prefixes, suffixes, middle names, and so on), nickname, addresses (postal, work, home, preferred), email addresses, and an assortment of telephone numbers. However, since vCard originated prior to widespread adoption of the Internet, there are few options for marking up multiple email addresses. The microformat community has created a work-around using the uniform resource locator (URL) property.

Another frequently used microformat is hCalendar. It is based on the iCalendar specification. iCalendar is designed as an interchange format of essential information for calendaring applications. It is used in calendaring applications, for example in Apple’s iCal and Microsoft Entourage. A simple event includes a name, description, date, location, and URL. The hCard microformat can be added to include contact information for the event. More complex events might also include start and end times, as well as detailed location information. An agenda from the Web Directions conference is used as an example of a complex event.

Throughout the book, Allsop provides guidance on how to use CSS in order to present the microformatted information. He also shows the reader how to incorporate seldom-used HTML markup in order to simplify the inclusion of CSS without the addition of unnecessary divs and spans.

Part 3 contains two case studies. The first is on Cork’d, a fairly new Web site using microformats. The site allows members to keep a wine journal; more specifically, this is a place for one to share his thoughts about various wines. In addition to the hCard microformat, the site also uses the hReview and the XFN microformats. The second example is Yahoo!, one of the largest publishers of Web content. Upcoming, acquired by Yahoo! in late 2005, hosts tens of thousands of events marked up in hCalendar.

The final part of the book contains information on developing microformats, which is done within the microformats community. The book concludes with three very useful appendices, containing a microformat specification reference, microformat design patterns, and a section on people, tools, services, and publishers.

Future Web browsers will be expected to demonstrate the ability to display data marked up using microformats. Allsop has done an excellent job of introducing the reader to microformats. He explains both how and why the use of microformats is important. I highly recommend that every Web professional becomes familiar with microformats. This book is an excellent resource with which to begin.