This is one of the most frequently asked deep learning interview questions for freshers in recent times. Artificial Neural Networks (ANN) can be of two main categories: Feed-forward neural networks and recursive neural networks. They are flexible to many possible variations based on – the learning rule, the inference rule and the architecture. Feed forward neural network can be described as per below diagram: Perceptron algorithm is a fundamental computational unit at heart of the Deep learning model. It’s a supervised learning algorithm for binary classification. There are many packages available for ANNs. In R, some of the packages are nnet, neuralnet, RSNNS, deepnet, darch, caret, RNN, Autoencoder, RcppDL, MXNetR and others for more specific tasks.