As a pre-med student, you will need to take many science classes. This normally includes chemistry, organic chemistry, biology and physics, along with their required labs.
You will also need to take psychology and behavioral science classes. The number and type vary, depending on the med school you're looking at attending and the college requirements for your major. You will spend the final 2 years of med school on psychology courses as well.
Chances are that you will need to take at least 1 full year of an advanced math class, such as calculus or statistics.
While not all med schools or colleges require it, many will have a number of humanities classes, such as sociology and English, which you will need to take. It's a safe bet that you will need at least 1 year of English.
Your GPA, especially in your math and sciences classes, will be closely examined by the med school you choose. The average GPA of a student who is accepted into med school is 3.5, with a minimum of 3.6 in the sciences and math.
The MCAT is the test you take at the end of your college courses. Med schools normally look for a MCAT score of between 8 and 12, depending on the competitiveness of the admission process for the med school you're looking at. The preparation you do in your pre-med classes will help you do well on the MCAT.
All college requirements will help to build your transcripts to get into med school. Once you attend med school, you will need to find somewhere for your residency. Depending on your final goal, you may also pursue a fellowship as another step before stopping your formal education.