(Editor's note: In this new recurring weekly feature, every Monday StLJN will share a couple of links to online resources devoted to music education, jazz history, and related topics.)
* Written to be understandable for beginners, but also a useful reference in general, "Music Theory for Musicians and Normal People" is a series of illustrated PDFs explaining the basics of music theory a page at a time. (You also can grab all the PDFs published to date as a single document.)
Topics includes everything from the basics of musical notation (pictured) to more advanced subjects like counterpoint, altered chords, extended harmonies, and more.
* If you're interested in the early history of jazz, the venerable Red Hot Jazz Archive is worth a look as a starting point for learning about bands and musicians who worked and recorded before 1930. (Though some might be put off initially by the site's design, which hasn't changed since the early days of the World Wide Web, the historical information contained therein is still good.)
The RHJA includes discographies and biographies of hundreds of early jazz musicians and bands, both famous and obscure, as well as a series of essays discussing various aspects of the music. Many of the entries also include audio files which, though regrettably presented in the now-antiquated Real Player format, are free for the listening.