How do classification and regression differ?

Classification is the task to predict a discrete class label.Regression is the task to predict a continuous quantity.
In a classification problem, data is labeled into one of two or more classes.A regression problem needs the prediction of a quantity.
A classification having problem with two classes is called binary classification, and more than two classes is called multi-class classificationA regression problem containing multiple input variables is called a multivariate regression problem.
Classifying an email as spam or non-spam is an example of a classification problem.Predicting the price of a stock over a period of time is a regression problem.