Artificial neural networks are computer software or hardware models inspired by the structure and behavior of neurons in the human nervous system. As a powerful learning tool, increasingly neural networks have been adopted by many large-scale information processing applications but there is no a set of well defined criteria for choosing a neural network. The user mostly treats a neural network as a black box and cannot explain how learning from input data was done nor how performance can be consistently ensured. We have experimented with several information visualization designs aiming to open the black box to possibly uncover underlying dependencies between the input data and the output data of a neural network. In this paper, we present our designs and show that the visualizations not only help us design more efficient neural networks, but also assist us in the process of using neural networks for problem solving such as performing a classification task. error bound, learning rate, training algorithm, hidden layer size, and the data vector used, are often chosen in a trial-and-error process.We believe visualization, which proves to help illustrate and understand the behaviors of complex systems, can also help us understand ANNs and design better ANNs. Previous attempts in using visualization to gain understanding into ANNs, as discussed in Section 3, mainly studied the weights and connections of a neural network and analyzed neural networks in isolation; the data used by the neural network were mostly not looked at.We therefore take a data-driven approach to the problem of visualizing ANN since gaining insights into a neural network requires the study of not only the network but also how it responds to the input data that it was designed to process. The methods we present enable the interactive exploration of both the input data and the neural network so as to gain more complete picture of how the neural network performs its task. The visualizations can also assist in the selection of network structure and other parameters for an assigned task, with the objectives to achieve better results and minimize the cost in terms of both space and time. Equally important is that the user can apply our visualization methods to study how neural networks use data, and gain further understanding into the potentially complex data relationships. In our work, we have applied visualization techniques to feed-forward neural networks trained with the back-propagation training algorithm [23], which is one of the most popular neural networks used for classification. Our designs and findings have helped us develop better intelligent visualization systems, and should also help others gain both understanding and confidence in using ANNs.