Soy sauce is one of the world’s most important condiments and has one of the longest histories. It’s also the foundation of much of Asia’s food. You’ll find it in almost every Asian kitchen and increasingly in Western pantries too. You may think of it as one particular sauce with a certain flavor profile, but there actually are many different kinds of soy sauce and they can vary greatly in terms of taste, texture, and appearance.We use it for stir fries and as a dipping sauce for sushi, but what exactly is soy sauce? And what makes Japanese soy sauce different from soy sauce that comes from China or other parts of Asia? What do you do when there are so many different kinds and a recipe you’re following doesn’t specify which soy sauce to use? In this blog post, we explore the world of Japanese soy sauce and attempt to answer some of these questions.In the most general sense, soy sauce is a condiment made from a fermented paste of soybeans, roasted grain, brine, and a type of mold called Aspergillus (or koji, as it is known in Japan). Its origins stem from the fact that, like many other condiments throughout history, it was first used as a way to stretch salt, which was once an expensive commodity. Soy sauce in its current form surfaced around the 2nd Century AD in China. This humble condiment soon spread throughout East and Southeast Asia where it continues to be the backbone of many Asian cuisines.Soy sauce made its way to Japan via Buddhist monks from China in the 7th Century. In Japan, soy sauce is known as shōyu. The original recipe for soy sauce was modified when it arrived in Japan, where an even ratio of soybeans and wheat was commonly used, though there were exceptions. In general, shōyu is thinner, clearer, and a little sweeter than Chinese soy sauce.But even amongst Japanese soy sauces, there are a lot of variations. There are five main types that you need to know:Koikuchi or Dark Japanese Soy Sauce: This is the most prevalent (and most mass-produced) shōyu you'll find in Japan. It's made of roughly equal parts soybean and wheat. It’s a good all-purpose soy sauce and can be used for marinades, cooking, and dipping.Usukuchi or Light Japanese Soy Sauce: This shōyu is saltier and lighter in color and it's made with amazake, a sweet liquid made from fermented rice. It is particularly popular in the Kansai region and is suitable for seasoning food without changing its color. It's also great for soups.Tamari: Tamari is well-known in the West for being a gluten-free soy sauce. However, while this type of shōyu is indeed made with little to no wheat, it can still contain traces and is not necessarily 100% gluten-free. Tamari was traditionally a liquid by-product made during the fermentation of miso - it's a darker, thicker, and richer soy sauce with a strong depth of flavor. It is closest to the original Chinese soy sauce that was first introduced to Japan. It is suitable for tare sauce and makes a great dipping sauce.Shiro: Shiro is, in a sense, is the opposite of tamari as it contains mostly wheat and not much soybean, giving it a very light color and a sweet flavor profile (even lighter than usukuchi).Saishikomi: Saishikomi means “twice-brewed” - it's produced by using previously made koikuchi soy sauce as the brine. It originated in the Southwest of Japan and has a dark red-brown color. It’s not as salty and has a sweeter, rounder flavor profile.