Vowpal Wabbit is a machine learning library that provides fast, scalable, and online learning algorithms. It can handle large datasets with millions of features efficiently using hashing and sparse representations. Unlike other libraries, Vowpal Wabbit is designed for online and active learning, allowing the model to be updated continuously as new data is processed. It performs linear learning rapidly using stochastic gradient descent and has been shown to scale to billions of examples and trillions of features.