Java is the programming language in which the low level code of all our software is written. These parts of our code involve things such as reading and writing datasets, drawing spectra, picking and displaying peaks, and mathematical and statistical routines involved in data processing and analysis. We use Java because it allows us to write software that runs without any changes on different computer operating systems (Windows, Linux, Mac OS X ...), it has extensive libraries that can be used to develop complex applications, and it has intrinsic capabilities that allow the programmer to take advantage of multi-core CPUs. Java's popularity means that there are great resources available to the the developer. Earlier versions of Java did not have great performance, but recent versions can run with speed similar to that of code written in languages like C.