You only need a cover letter when a job posting specifically asks for one.

Cover letters have a defined structure.

When writing your cover letter, you should...copy and paste the first and last paragraphs, but tailor the rest to the employer..

An employer uses your cover letter to... judge your writing ability, understand why you are applying for the job and evaluate your ability to take directions.

Your cover letter should be no more than 1 page.

A cover letter can be handwritten.

Your cover letter should only focus on why you want the job and what you can do for the employer.

An employer will accept a cover letter with one typo.

A speculative cover letter is sent to a company that has advertised jobs

Your cover letter should be addressed to the company's name e.g. Dear Google