Training Data. Algorithm 1 (solid line) models the training data perfectly, with no error. Algorithm 2 (dashed line) is much more generalized and does not model the training data as well as Algorithm 1.  
  Part of: Thessen A (2016) Adoption of Machine Learning Techniques in Ecology and Earth Science. One Ecosystem 1: e8621. https://doi.org/10.3897/oneeco.1.e8621