Use for questions about the online machine learning (aka out-of-core or incremental) technique. Use with the main [machine-learning] tag and with an appropriate language tag (e.g. [python]) where applicable.
Online machine learning is different than other approaches, such as batch learning techniques, which generate the best predictor by learning on the entire training data set at once.
It is a common technique used in areas of machine learning, where it is computationally infeasible to train over the entire dataset, requiring the need for out-of-core algorithms.
It is also used when it is necessary for the algorithm to dynamically adapt to new patterns in data, or when the data itself is generated as a function of time, such as "stock price prediction" for example.
In scikit-learn, for example, the SGDClassifier features an implementation of online learning.
