With each successive generation of processors, the number of developers who want to program in assembly language is diminishing. Further, every generation has required a new round of assemblers, compilers, and a new set of developer expertise. Tools vendors recognized a need to provide developers with software tools to develop every processor release with a variety of functionality, a storehouse of optimized code for developers to draw upon. Thus performance libraries targeting several application domains have developed. This article discusses the basics of performance libraries, and how different areas of computer science benefit.