In this guide, we will discuss the importance of a cover letter and provide you with tips and tricks to help you craft an effective one. The purpose of a cover letter is to make a compelling case for yourself as a candidate for a particular job, and it complements what's in your resume.Study this sample cover letter and explore the dropdowns below to learn how to craft a quality document. Cover letters are one-page documents consisting of at least three parts. Review our materials below to learn how to write and format resumes, CVs, and cover letters as well as tailor them to specific job descriptions.