What Is ?

Cover letters

A cover letter is a letter of introduction attached to, or accompanying another document such as a résumé or curriculum vitae

For employment
Job seekers frequently send a cover letter along with their curriculum vitae or application for employment as a way of introducing themselves to potential employers and explaining their suitability for the desired position. Employers may look for individualized and thoughtfully written cover letters as one method of screening out applicants who are not sufficiently interested in their position or who lack necessary basic skills.

Cover letters are typically divided into three categories:

Other uses
Resume cover letters may also serve as marketing devices for prospective job seekers. Cover letters are used in connection with many business documents such as loan applications (mortgage loan), contract drafts and proposals, and executed documents.

Cover letters may serve the purpose of trying to catch the reader's interest or persuade the reader of something, or they may simply be an inventory or summary of the documents included along with a discussion of the expected future actions the sender or recipient will take in connection with the documents.

that's it!