It highlights your accomplishments to show a potential employer that you are qualified for the work you want. It is not a biography of everything you have done.
Its purpose is to get you an interview.
Common parts of a resume
1) Name— students must put their name in at least 14-point size (or 2 to 6 points larger than the rest of the text), making it easy for employers to see the name. Place the name on the first line of the page. The traditional place to put the name is at the top center, but many now prefer to right justify it so when their resume lands in a folder, their name is clearly visible.
2) Address—If they are still in school, students must be sure to include both their school address and their home/ permanent address where they can be reached during school vacations or after they graduate from college.
Students must also avoid post office boxes because the employer might suspect that they are hiding something.
3) Email—Students must include an independent email address that is not associated with their school (or work), so they can check their email even during school vacations if they are still studying. Also when typing, they should avoid the (automatic) hyperlink under their email address— the line under their email should not be included. However, if students use their online account—say, from Google/ Gmail—they must make sure their member profile doesn’t contain anything incriminating, embarrassing or inappropriate.
4) Phone number—A mobile/cell phone number or landline number is a must. If they don’t have one or if their contact number is likely to change soon, students must list the number of a family member or close friend willing to function as their answering service. And if in case they are already working and they leave a work number, they must be certain that they won’t get busted for conducting a job hunt on the job.