A cover letter is a document sent with a job application to introduce the applicant and highlight their qualifications. It typically accompanies a resume and provides a more personal touch, allowing candidates to explain their interest in the position and how their skills align with the company's needs. In a cover letter, applicants can showcase their personality and enthusiasm for the role, making it an essential part of the job application process. It should be tailored to each specific job and company, demonstrating the applicant's understanding of the organization and its goals.