11.5 Programming languages
A computer program is written in a programming language and contains the instructions that tell the computer what to do. Developers write new software using specialised programming languages. The resulting programs (or 'source code') can be converted into the low-level instructions understood by the processor. There is a wide range of programming languages to suit different types of task; if you look at advertisements for programming jobs in newspapers or online you will get an idea of which languages are being widely used. Languages such as C++, Visual Basic and Java are in demand at the time of writing (early 2005).
Computer software falls into two main categories: operating systems and applications.