What is the oud, the Moroccan lute?

The oud is probably the instrument visitors picture when they imagine Arabic music, even if they do not know its name. It is a pear-shaped lute with a deep rounded back like half a teardrop, a short neck bent sharply back at the pegbox, and — crucially — no frets. That fretless fingerboard is the whole secret: it lets the player glide between the microtones, the quarter-tones that sit between the notes of a Western scale and give Arabic music its yearning, in-between quality.

Played with a long thin plectrum traditionally cut from an eagle feather (now usually plastic), the oud has a warm, woody, slightly melancholy voice. In Morocco you hear it leading the melody in Andalusian orchestras and in malhoun, the sung-poetry tradition, where it traces the vocal line and then takes flight in improvised solos called taqsim. A skilled player can make it weep, race or whisper, and a good taqsim in a quiet room is genuinely spine-tingling.

Unlike the guembri, which belongs to the Gnawa, the oud is the classical, urbane instrument of the imperial cities — Fes, Tetouan, Rabat. I send travellers to Fes for it, especially around the Fes Festival of World Sacred Music in spring, when Andalusian ensembles perform in palace courtyards under the stars. You will also catch it in the better riad dinners and at concerts in the medina, often paired with violin, qanun and percussion.

If you fall for the sound, the artisan quarters of Fes and Marrakech still have a few luthiers building ouds by hand, and watching them bend the ribs for the bowl-shaped back is a craft worth seeing. The oud is the thread that ties Morocco to the wider Arab and Mediterranean world — the same instrument, slightly different accent, from Casablanca to Cairo to Andalusia.