The most common pre-med classes are based in math and science, and almost always include calculus, physics, and chemistry in addition to more medicine-specific courses like human biology and anatomy. In general, any undergraduate class that will prepare a student for a career in medicine can be considered a pre-med class. While math and science classes are the most common, courses that focus on language and communication, psychology, and sociology are also useful.
Pre-med classes occupy a rather amorphous category of university courses that students either must take in order to attend medical school, or choose to take as a means of preparing for further medical education at some point in the future. Classes focused on calculations, formula conversions, and organic processes are the most common. Most of the time, pre-med classes can be taken by anyone and are not limited to those pursuing medical school. Student intent is one of the main things that transforms ordinary math or science classes into specifically pre-med classes.
Foundational courses like basic biology, general chemistry, and human anatomy and physiology are nearly always considered pre-med classes. So too are basic math courses like calculus and statistics and conceptual science courses such as physics. Most of the time, pre-med students must master all of the basic survey-type classes in the math and science disciplines.
Basic courses may not themselves directly relate to medical studies, but they usually serve as foundations for more nuanced offerings in later years. Genetics and organic chemistry are often very useful for burgeoning doctors, for instance. Advanced labs are usually a good idea, as well.
Chemistry labs and biology labs are often some of the most hands-on science experiences undergraduates have, and they usually bear the closest resemblance to the sort of work that will be done in medical school. Conceptual work like that done in physics labs can carry value, as well, as it helps students experience theorems and principles in addition to understanding them on paper. Pre-med students often elect to take as many lab courses as possible in order to enter graduate work with the most knowledge and the biggest academic edge on their peers.
Not all pre-medical classes are in the science realm, however. Language arts and literature courses are good ways of honing communication skills, which are essential for patient contact and interaction once in practice. Courses in psychology, sociology, and the social sciences can also be beneficial. Doctors must be sharp in the math and science realms to succeed in medical coursework, but a well-rounded education is often necessary to be effective in practice.