I never really understood the true significance of a cover letter, but after doing much research they have come to make sense to me. When someone writes a cover letter, they are expressing their communication skills through their writing. Depending on how well the cover letter is written will determine whether or not an employer will proceed to reading your resume.
It is wise to have a standard cover letter saved on your computer so it can be tweaked when applying to different positions. Your cover letter should emphasize why you would be a good fit for the position and should highlight your best assets. One important thing to remember is to keep it brief, which can be challenging for many. Your cover letter should never be any longer than a page because it is intended to be a quick read.
Keep in mind that cover letters can make you stand out to an employer and can convince them to review your resume. There should be no grammar or spelling errors, so make sure your cover letter is free of those! Also, let your writing style shine, show authenticity because after all, they should get an idea of who you are through the writing.