We learn by doing. We learn mathematics by doing problems. This page covers a wide variety of problems in the following branches of Mathematics. It is mainly intended for students studying the basic principles of Mathematics. However, given its organization, level, and selection of problems, it would also be an ideal choice for tutorial or problem-solving seminars, particularly those geared toward any exam. The page is also suitable for self-study. Each section of the page begins with relatively simple exercises of an specified branches of mathematics, yet may also contain quite challenging problems. Very often several consecutive exercises are concerned with different aspects of one mathematical problem or theorem. This presentation of material is designed to help student comprehension and to encourage them to ask their own questions and to start research. The collection of problems in the page is also intended to help teachers who wish to incorporate the problems into lectures. Solutions for all the problems are provided.