Linked from
The 24 pages that link to Overfitting, each with the reason it gives.
Machine learningRelated: A model can memorize examples rather than learn patterns that generalize.
Neural networkRelated: Excessive fitting can make a network unreliable beyond its training examples.
Model selectionRelated: It explains why the best-fitting candidate need not be the best model.
Scientific modellingRelated: Overly flexible models can mistake noise for stable structure.