RNN is abbreviation of Recurrent Neural Network which is a class of artificial neural net with feedback.

Recurrent neural network is a class of artificial neural net with feedback. Feedback means that elements are connected by loop. It allows to organize internal memory and treat accidental inputs.

For more information look for these pages:

  1. https://en.wikipedia.org/wiki/Recurrent_neural_network

  2. https://colah.github.io/posts/2015-08-Understanding-LSTMs/