Use the cover letter to explain and nullify any negative effects that might be created by chronological gaps, a lack of experience or a long absence from work. Mention outside work, volunteer experience or other marketable skills that show you spent your time out of the workplace productively. End the letter by initiating the next step. Your resume might be scanned into a computer database, in which case your cover letter will be scanned, too. Stick to basic font styles that are easy for the computer to read.
Some employers discourage electronic cover letters because they take up too much computer space.
However, a cover letter helps employers after they've called up your skills in a data search. Find out beforehand, if possible, what the employer prefers. You'll want to list the key words prominently in your scannable cover letter, either with a separate key word listing or by mixing them into the first few sentences. Read more about scannable resumes.