Before he was Black Lightning, Jefferson Pierce was an Olympic decathlete, and over the course of this story we see him doing a few decathlon-type things. Jefferson's two daughters are Anissa (Thunder of the Outsiders) and Jennifer (Lightning of the JSA). Jefferson was also a high school teacher for a while, and later the U.S. Secretary of Education under the Lex Luthor administration.OK, so now you know who Black Lightning was. I certainly didn't know in this granular level of detail before — and nor do many casual comics readers who haven't got what amounts to an advanced degree in comics like Wolk. And yet knowing it enriches the experience of the issue, since DC Comics characters are often decades old and rather complex. Neal Stephenson reflects the annotation urge in his recent novel Anathem. He's put part of the novel's extensive glossary online, giving readers a place to go to look up some of the words he coined to describe life among the science monks on another planet. And these kinds of annotations transcend the world of comics and scifi nerdery. Music journalist Alex Ross released a book last year about twentieth century music called The Rest is Noise, which he supplemented by creating an elaborate, stand-alone annotation website. A massive compendium of twentieth-century musical terms, with definitions and illustrative sound files, his site can be read alongside the book to enrich the experience immeasurably. Or it can be absorbed on its own, as a musical dictionary. There are many other examples: Some created by the authors of books, and others like Wolk's created by knowledgeable readers. These electronic footnote sites do not replace books, but they make reading feel like an erudite discussion rather than a lecture. They also make it possible for authors to write far more complicated and nuanced books. Confused readers have an easy place to go if they want to understand a crucial reference or idea, while in-the-know readers can have fun adding their own annotations to the web. A culture of rampant annotators isn't exactly what you'd expect from the web, which is still in many people's minds antithetical to book culture. And yet it seems that our newest media have reinvigorated what often seems a lost art. The art of footnoting.