I discovered the oud while on vacation in Istanbul and was instantly hooked. The oud is one of the most well known and highly regarded instruments of the Near and Middle East, and has been around for centuries. Yet relatively few people outside of the Near East, Middle East, North Africa, and some in the Balkans have ever heard or seen an oud. This is unfortunate, as in my view the oud is one of the most beautiful instruments there is.
The oud is the ancestor of the European lute, but it is played with a pick. Like the violin and cello, it has no frets, allowing an infinite variety of tones to be played. In Ottoman/Turkish music theory there are 53 possible tones per octave, rather than the 12 that are found in Western music. And in Arabic music theory there are 24 tones per octave. In reality, many of the tones are not fixed in either system, and move up and down depending on the composition, improvisation, or the taste of the musician.
The music most commonly played on the oud is based on the makam system, an incredibly rich, varied, and complex modal system. Each makam has a "scale" composed of various trichords, tetrachords, and/or pentachords, particular tonics or starting notes, particular dominant notes, and a particular melodic direction. There are hundreds of makams, each with unique and different flavors, and experienced musicians may be comfortable with 50 or more.
Due to the size and diversity of the Ottoman Empire, there is a great variety of traditional repertoire for the oud that dates back many centuries. Famous Ottoman composers came not only from Turkey and the Middle East, but also from Greece, Armenia, Central Asia, Northern Africa, and Europe. In addition to composed pieces in different genres (classical/art music, songs, dance music, sufi hymns, etc.), improvisation is an essential part of makam music.
There are a number of websites about the oud in English, and an active discussion forum where anyone interested in the oud can find a great deal of information. The purpose of this site is to expose more people to the oud, and eventually to provide some free information that might be useful to new players. Makam music is extremely complex and difficult to fully grasp without in-depth study. That combined with differences between "Turkish" and "Arabic" ouds, different tunings, different methods of notation, and different approaches to theory make learning the oud and makam music somewhat daunting. As a teacher myself (not of music), I hope to be able to simplify a few concepts here that took me longer to figure out than necessary.