Convolutional Neural Networks got inspired from the way our human visual cortex works (human eye) and classifies images like dog, cat, man, women, car, jet, or computer.
Convolutional Neural Networks are used for the classification of images.They do a great job because the training of the neural network breaks up the image into component parts and does classification based on various parts of the image. So a dog or cat or numerical number is learned by the various properties of the image. Here are some great links:

best tutorial: Convolutional Neural Networks (CNNs / ConvNets)

Google’s TensorFlow neural networks

Visualizing and Understanding Deep Neural Networks by Matt Zeiler

Visualizing and Understanding Convolutional Networks

Deep Learning Reading List

Google’s TensorFlow: Convolutional Neural Networks