Alternatively, when a part of a pattern and a classification are given, or just a part of a pattern is given, the network is asked to complete the pattern. The neural network attempts to simulate the human brain. The human brain has front-end subsystems and can only handle preprocessed information. The same is also true for neural networks. Neural networks use neural data.
User data depends on the application.
The information processed by a neural network has to be prepared by a front-end subsystem. This is called data encoding. A neural network can not usually handle the user-application data directly. This is called data decoding. Front-end systems are basically a language translator.