How does a learning curve give insight into whether the model is under- or over-fitting?
A model that is underfit will produce evaluation metrics that are poor on the training data alone, such as high RMSE or misclassification rate.
bias
What is the Bias/Variance Tradeoff?
The bias/variance tradeoff refers to the challenge of finding a model that both performs at a high level of accuracy on the data on which it is trained (bias) while at the same time generalizes well to unseen data (variance)