As a first year student, you should definitely not be thinking about the match right now. Concentrate on doing as well as you can in terms of grades and learning the basic sciences in the pre-clinical years of medical school.
With that said, I will say a few words about the match because it is good to at least know what it is. In the early part of senior year of medical school, you will submit an electronic residency application service (ERAS) form in coordination with the medical school dean's office. You will designate electronically which programs you want to apply to. Programs will electronically receive your application and if you meet their requirements (based on grades, medical board exam scores, letters of rec, extracurrics, research, school pedigree, etc etc), you will be invited to interview. Most people end up interviewing at 10-40 places depending on field of interest. Internal medicine programs are larger so applicants can apply to fewer places and still successfully get a residency. Surgery and surgical subspecialties require more applications and interviews because program sizes are smaller.
At the conclusion of interview season in the early part of senior year of medical school, you will submit a computerized ranking of residency programs that you interviewed at and liked in order of how YOU like them. The programs will submit their own list of applicants in the order the that PROGRAM likes the applicants. The computer algorithm will then match the applicants to the residency programs as best as possible, with first priority going to trying and getting every applicant into his/her top choice residency program. After the computer is done, everyone will be informed. Hopefully everyone will be happy. Most people will match at their top 3 choices, but inevitably not everyone can match at their top choices and some people will go programs lower on their list. A small minority of applicants will go unmatched to any program and those people will participatd in the post-match "scramble" for unfilled residency spots.
Most residencies use the NRMP which is also known as the regular match. Some fields like Urology, Opthalmology, neurology, military and a few others have their own match programs and computers and do not use NRMP. These are also known as the "early match" fields because generally their application season, interview season, match day occur a little earlier in senior year of medical school than the regular NRMP. ENT used to have their own match but have this year joined the NRMP.
When you register for the match in coordination with your medical school, (which all US medical students must do if they want a residency), then you are bound by contract to go to whichever program you match to. Similarly, the programs are bound to take whichever applicant the computer ultimately matches to their program.
Some people love the match system, some people hate the match system. Some people have tried to sue the match system, the government/congress have not allowed the NRMP to be sued for various reasons. Bottom line: the match system is here to stay.
So anyway, just work hard in med school, learn as much as you can, try to find a field within medicine that you like, find a mentor or adviser in that field, and eventually you will get there. There will be times in medical school where you might miserable and depressed due to the constant studying and feeling overworked, but you will have solace through sharing the rough times with classmates, friends, and family, and you will eventually make it through medical school as many generations before you have. The first 2 years are the hardest in terms of constantly having to study. In the middle of 2nd year or at the beginning of 3rd year (depending which school you attend), you will enter the hospital and clinics and at that point life will become fun again and you will be doing what you actually came to do.
Then senior year of med school will come and it will be a special time in life and you will be euphoric.
For now, just have fun with your family and friends, and know that when medical school comes you will be working harder than you can imagine but you will make it through, learn a lot, and have fun along the way.
