Wagyu beef comes from the word “Wa Gyu” which in Japanese Language means “Japanese Cattle”. This article is to share in a simple way, so more people can understand what is Wagyu. There are four Wagyu breeds, the Japanese Black, the Japanese Brown, the Japanese Polled and the Japanese Shorthorn. The Japanese Black is the one that’s being developed and famous for it’s special taste/sweetness/umami and beautiful marbling on the meat. Generally when we speak of Wagyu, in the rest of the world, we are referring to this breed.
This Japanese Black beef or Black Wagyu is being breed and developed in different prefecture of regions within Japan. The examples of prefectures are Kagoshima, Miyazaki, Okayama, Hyogo or Kobe etc. This is where we get the famous name of the wagyu. 
The beef also comes with different rating A5 being the best, then A4, A3 and the rest. For mix breed or some named it wagyu hybrid, we have grade like F1, F2 etc which is considered a way lower grade compare to A5 and inconsistent in quality. Even within A5, there is a different BMS rating. BMS rating of 11 and 12 are the rarest. it was said, only 1 out of 100 A5 cattle perhaps will get this special rating. The price of the meat is also depending on the part of the cattle which i will not go in detail here. Basically, the loin part (sirloin, ribeye and tenderloin) is the most treasured part for steak and is in very high demand, therefore the higher price.
Wagyu is also available in Australia. This is basically a cross breed from Japan’s breed and it is breed in Australia. In Australia, the quality rating use for the marbling is a little bit different. Australian is using the BMS rating. BMS 8 and 9 is the highest available wagyu from this region. But the taste and marbling effect is totally different compare to the wagyu from Japan. The Australian Wagyu taste are more beefy compare to Japanese Wagyu. Some of the consumer prefers this because it is not too fat and still have the superb tenderness compare to other Australian beef. And to some the price is more acceptable. There are in general 50% cheaper compare to Japanese Wagyu.
In other part of the world, USA, UK and South America, there are also some experiment to breed Wagyu using the Japanese cattle. However, it has not been very popular yet and it is not available in Malaysia. Hope the above will give you some simple explanation and good knowledge of Wagyu.