What is an epoch?

An epoch is one complete pass through the entire training dataset during model training. If you have 10,000 samples and a batch size of 100, one epoch consists of 100 weight update steps (iterations). Training usually runs for multiple epochs until the model converges (loss stops decreasing significantly). Too few epochs leads to underfitting; too many leads to overfitting. Early stopping monitors validation loss and halts training when it stops improving, choosing the best epoch automatically.