Think of a resume as “self-advertisement” that sums up your experience on one page. Your resume is one of the most important pieces of your job application. It gives the hiring manager an overview of the qualifications you have for the job for which you’re applying. You should also familiarize yourself with the difference between a resume and a cover letter.
In addition, functional or combination resumes may also be useful if you are trying to draw the readers attention away from something – namely, large gaps in your work history or detours into unrelated fields.