Your CV should always be accompanied by a covering letter. This should be succinct and carefully targeted to the specific company and/or the position you are applying for. 

If your covering letter is written well, then there should be less need to alter your CV substantially for each application you make.

If you are responding to a job advertisement

the letter can communicate your understanding of the requirements of the particular position they are offering and your reasons for applying to the company, as well as indicating your suitability for the job.

If you are making a speculative application or general enquiry

the letter can express your interest in the particular company, and your reasons for seeking employment there.

You can also suggest what you could have to offer the company.

 

It is worth taking time and care over a covering letter, as it sets the context in which an employer will read your CV. Some employers will ask for hand-written letters, but otherwise you should type yours, and ‘top and tail’ it by hand. Finally, as always, keep it brief and simple!