# Is LSTM a subcategory of RNN?

Is the LSTM-Architecture a subcategory of RNNs? Or are they totally different?

Literature doesn't seem to be unitary on this. This figure appears to explain the models to be alternatives, but I thought of them otherwise (LSTM to be a subcategory of RNN)

LSTM as a subcategory of RNN is mentioned in the Wikipedia article on LSTMs:

Long short-term memory (LSTM) is an artificial recurrent neural network (RNN) architecture...

However, it is also common to see "RNN" used as a short-hand for a kind of "Vanilla RNN" or "basic RNN", where one or more layers have weights connecting the layer to itself (its own activations from $$t-1$$ are concatenated to the external inputs at $$t$$), and there are no other gates or special combinations, just those recurrent connections.