Teachable Machine splits your samples into two buckets. That’s why you’ll see two labels, training and test, in the graphs below.
Training samples: (85% of the samples) are used to train the model how to correctly classify new samples into the classes you’ve made.
Test samples: (15% of the samples) are never used to train the model, so after the model has been trained on the training samples, they are used to check how well the model is performing on new, never-before-seen data.
Underfit: a model is underfit when it classifies poorly because the model hasn't captured the complexity of the training samples.
Overfit: a model is overfit when it learns to classify the training samples so closely that it fails to make correct classifications on the test samples.
Epochs: One epoch means that every training sample has been fed through the model at least once. If your epochs are set to 50, for example, it means that the model you are training will work through the entire training dataset 50 times.