A member of a class of software that is "trained" by presenting it examples of input and the corresponding desired output. For example, the input might be a magnetic anomaly and the required output the depth to the source of that anomaly. Training might be conducted using synthetic data, iterating on the examples until satisfactory depth estimates are obtained. Neural networks are general-purpose programs which have applications outside potential fields , including almost any problem that can be regarded as pattern recognition in some form.