A resumes is a document that states your skills & abilities to a potential employer.
Resumes are used by potential employers to choose who is a possible candidate for the job a job. It is very common that 100s per resume for a job, that was posted in a newspaper or Internet. The employer can't interview 100s of people so they choose a few people to interview based on there resume.
You can think of a resume like a advertisement for yourself to a potential employer.
There is no perfect resume, just like there are no perfect jobs, or perfect employers. but there are so jobs and employers that come come to perfect & it is the same with resumes, there is no perfect resume, but we can do the best we can to come as close to perfect as we can.