1. Knowledge - Every job has a minimum standard that is expected but the requirements are different, depending on the job. Sometimes a university or college degree is required and documentation to verify that a program has been completed will be necessary. There might be a minimum high school grade level that is needed. In some occupations, only general knowledge is acceptable and specialized training may be provided on-the-job by the employer. You may be required to take some tests along with participating in an interview both of which are designed to verify that you meet expectations.
2. Skills - These are things that are necessary for the job that you have already learned how to do. They will vary, according to the tasks that will be assigned, but maybe consist of things like having a driver's license, being able to use specific software programs or being fluent in another language. Be sure that you list these on your resume.
3. Abilities - Your references should be willing to attest to specific things that you have accomplished in other settings. You might, for example, have been the team leader for a special project or received an award for volunteerism. Perhaps you have had several years of experience working in a specific field or operated a successful home business. What you have done in the past is a good indicator of what the employer can expect of you in a similar situation in the future.
4. Compatibility - There are times that you might have all the knowledge, skills and abilities to do the job but there is something that intereferes with this. You might find that adjusting to a new location or climate is daunting. Perhaps you have some limitations that would prevent you from meeting the physical demands. Maybe your personal values clash with those of the company who is doing the hiring. Even if you "can" do the job maybe you "won't" want to do it. Or, the employer might think that you are not suitable or will not fit in with the other staff members.
Usually, when a company is hiring, they require that you meet the criteria for all of the above categories so you will not only have to ensure that each is covered in your resume but also have examples that you can use in the interview.
And, of course, there are always situations where you appear to be fully capable of doing the job but come up against other people who have similar or even better qualifications.
The best things that you can do, if you are looking for work, are to keep improving your resume by enhancing your qualifications and continue to improve your interview skills.
Never consider it a failure if you go through the process and are not offered a job. Each time you do this, you have an opportunity to practice presenting yourself and with practice, you will get better and better at it!