The resume is a selling tool that outlines your skills and experiences so an employer can see, at a glance, how you can contribute to the employer's workplace.
Your resume has to sell you in short order. While you may have all the requirements for a particular position, your resume is a failure if the employer does not instantly come to the conclusion that you "have what it takes." The first hurdle your resume has to pass--whether it ends up in the "consider file" or the "reject file"--may take less than thirty seconds.
The most effective resumes are clearly focused on a specific job title and address the employer's stated requirements for the position. The more you know about the duties and skills required for the job--and organize your resume around these points--the more effective the resume.
You will need information to write a good resume. Not just information about jobs you've held in the past but also information to select the most relevant accomplishments, skills and experience for THIS position. The more you know about the employer and the position, the more you can tailor your resume to fit the job.
from http://jobstar.org/tools/resume/res-def.php (accessed 4/16/2014)