title: What does the standard Keras model output mean? What is epoch and loss in Keras?
body: <p>I have just built my first model using Keras and this is the output. It looks like the standard output you get after building any Keras artificial neural network. Even after looking in the documentation, I do not fully understand what the epoch is and what the loss is which is printed in the output.</p>
  
  <p><strong>What is epoch and loss in Keras?</strong> </p>
  
  <p>(I know it's probably an extremely basic question, but I couldn't seem to locate the answer online, and if the answer is really that hard to glean from the documentation I thought others would have the same question and thus decided to post it here.)</p>
  
  <pre><code>Epoch 1/20
  1213/1213 [==============================] - 0s - loss: 0.1760     
  Epoch 2/20
  1213/1213 [==============================] - 0s - loss: 0.1840     
  Epoch 3/20
  1213/1213 [==============================] - 0s - loss: 0.1816     
  Epoch 4/20
  1213/1213 [==============================] - 0s - loss: 0.1915     
  Epoch 5/20
  1213/1213 [==============================] - 0s - loss: 0.1928     
  Epoch 6/20
  1213/1213 [==============================] - 0s - loss: 0.1964     
  Epoch 7/20
  1213/1213 [==============================] - 0s - loss: 0.1948     
  Epoch 8/20
  1213/1213 [==============================] - 0s - loss: 0.1971     
  Epoch 9/20
  1213/1213 [==============================] - 0s - loss: 0.1899     
  Epoch 10/20
  1213/1213 [==============================] - 0s - loss: 0.1957     
  Epoch 11/20
  1213/1213 [==============================] - 0s - loss: 0.1923     
  Epoch 12/20
  1213/1213 [==============================] - 0s - loss: 0.1910     
  Epoch 13/20
  1213/1213 [==============================] - 0s - loss: 0.2104     
  Epoch 14/20
  1213/1213 [==============================] - 0s - loss: 0.1976     
  Epoch 15/20
  1213/1213 [==============================] - 0s - loss: 0.1979     
  Epoch 16/20
  1213/1213 [==============================] - 0s - loss: 0.2036     
  Epoch 17/20
  1213/1213 [==============================] - 0s - loss: 0.2019     
  Epoch 18/20
  1213/1213 [==============================] - 0s - loss: 0.1978     
  Epoch 19/20
  1213/1213 [==============================] - 0s - loss: 0.1954     
  Epoch 20/20
  1213/1213 [==============================] - 0s - loss: 0.1949
  </code></pre>