There are many steel types out there so it is nice to know a bit about them before you buy a knife. Here are the types of steel that I carry in the shop, if you have any further questions please do not hesitate to contact me and I will do my best to answer any questions.
Generally, Japanese knives are made with harder steel than some of your more common western knives. This is great because it means you can sharpen to a more acute angle, and they get much sharper. The downside to having hard steel however, is that it can chip. I think this is a small price to pay if you want a proper sharp knife. Steel hardness is tested on the Rockwell scale. The Rockwell test determines the hardness by measuring the depth of penetration of an indenter under a large load compared to the penetration made by a preload. So the higher the number, the harder the steel.