The cover letter. Perhaps the most controversial job search document. Okay, if not the most controversial then it's at least the one that annoys people most. “What should I put in it?" “Do I really need to include this?" “Will anyone actually read this?" “What's the point if I'm including my resume?"
Personally speaking, I always recommend including a cover letter, especially if the job is related to communications, marketing or any profession that relies upon you being well-spoken and having exceptional writing abilities.
Here is our infographic on cover letters and how to make one that is eye-catching to a hiring manager - click on it to see the full version: