Machine learning is a branch of artificial intelligence that deals with creating systems that learn from stimuli they receive as input, providing guidance, for example in classifying objects, faces, sounds and situations, on previously unobserved stimuli. The neural network is based on a computational model whose layered structure is intended to mimic the structure of neurons in the brain. The strength that governs the behaviour is the way in which the individual elements or neurons are connected to each other and the ‘weight’ of these connections. The strength of the connections, or weights, are adjusted automatically during the training procedure. This training continues until the network performs the desired activity correctly.