Four countries have united to propose couscous as a world heritage dish -- Tunisia, Algeria, Morocco and Mauritania. The origin of the dish is Berber and the word is an onomatopoeia. Coussss coussss is the sound that the semolina makes as you swish it around in a big flat pan so that all of the grains are perfectly separated before being cooked.
All of the types of couscous are included in the request -- meat, seafood and vegetarian -- because it started as a dish for the poor, and you used whatever vegetables or meat that you had on hand. Anyway, it is the second most popular dish in France. In school cafeterias, company canteens or as the plat du jour in cafés, you can often expect to find it on Thursdays. There is no particular reason for that, but it just happened over the years, except of course in all of the couscous restaurants where you can have it seven days a week.
I am just sorry that the semolina has spread all over the world but with so many people not having the slightest idea of what to do with it, so they just make it instead of rice or something.