The purpose of Job Cover Letter is to;
Introduce yourself to the employer.
Demonstrate your interest in the Company and Vacancy.
Motivate why you would be a good fit for the job.
Further explain/elaborate certain aspects of your CV.
Encourage the recruiter to read your CV.

Thank you, i want to know if this is universal, like the same in UK & Europe. You know how different locations have different CV formats and things they look out for in a CV, or is this just a generic format.