1. Machine learning algorithms can be used for classification or regression tasks, with classification predicting a discrete label and regression predicting a real number. 2. K-nearest neighbors (KNN) is a simple supervised learning algorithm that can be used for classification by finding the nearest training example to a new data point and predicting the same label. 3. Naive Bayes classification is another simple algorithm that uses Bayes' theorem to classify text documents based on a "bag of words" representation, making the assumption that words are conditionally independent given a class.