The text book case of applying to med school is as follows:
I. Through the course of your undergraduate career from freshman to junior year you should have befriend many professors so they can write you letters of recommendation. You should have also done some clinical work as well as other extracurricular activities.
II. Junior Year in college: Take MCAT exam in April. It is a wonderfully exciting exam that takes up your entire day. You study for about 2-3 months (and still feel you're not ready..hehe). It encompasses-
1. Physical Sciences (Physics and General Chemistry)
2. Verbal Reasoning
3. Writing Sample (2 Essays)
4. Biological Sciences (Biology, Genetics/Evolution, Organic Chemistry)
About a month and a half later you get your MCAT scores back...hurray you did good!
III. June of your Junior year, you set up your AMCAS (American Medical College Application Service) application. This is your primary application which will be sent to all med schools you apply to. This is an online process. You put in your GPA, MCAT, personal statement (why i want to be a doctor), extracurriculars, blah blah blah, and of course your personal info. Click send, and you also forward all your transcripts to AMCAS, and you sit and wait. AMCAS costs $150 for the first school, and $30 for every other school afterwards.
IV. If schools think you're good enough after going through your AMCAS application they will send you a secondary application. Some schools automatically give you a secondary application so thats kinda cool. The secondary would either just ask you to send more info like letters of recommendation, updated GPA, etc, and/or ask you more questions. But definately they will ask you to send more $$..haha. So you will be paying for every secondary you get.
V. Through divine intervention by whatever god you believe in, and with a great amount of luck, they may review your secondary and ask you for an interview. You fly, drive, walk to where ever you applied to. Talk to them, take a tour, and then go home. The members of the admissions committee will then meet to talk about you and your application. If all goes well they send you a letter of acceptance.
Pretty much i believe going from Step I to Step V, it will go from 5000 people to just 500. Depending on the class size, after interviews they'll probably accept between 100-250 people. Good times. Additionally, by the time you figured out you got in or not, you're a senior and almost ready to graduate. Of course this is the TEXTBOOK way, many people don't do it this way. Hence the term "non-traditional applicant".