How does deep learning work?

Deep learning involves using an artificial ‘neural network’ — a collection of ‘neurons’ connected together.

An artificial neuron has one or more inputs. It performs a mathematical calculation based on these to deliver an output. The input-output function can vary. A neuron may be:

• a linear unit (the output is proportional to the total weighted input;
• a threshold unit (the output is set to one of two levels, depending on whether the total input is above a specified value); or a
• sigmoid unit (the output varies continuously, but not linearly as the input changes).