After companies had done well with Six Sigma for a few years, they saw that what was holding the back in terms of quality and cost was the design of products. So DFSS was developed. It is basically a toolset and methodology for designing new products and services to maximize quality and minimize cost. It uses quite a bit of software to do things like model the product’s performance characteristics, perform statistical tolerance generation, and other cool stuff. It was the big second wave of Six Sigma related stuff.