Copyright is the set of exclusive rights the law gives the authors of original works, such as music, lyrics, texts and images, over copying, distributing, performing, adapting and making them available online. Under the Berne Convention of 1886, protection may not depend on formalities, so in most countries copyright arises automatically once a work is created. The US Copyright Office likewise describes registration as optional, although it is generally needed before suing over a US work.
Copyright protects expression, not ideas, and in music it applies separately to the composition and to each recording of it. Its length varies: in the EU, including Italy, authors’ rights generally last for the author’s life plus 70 years, the same basic term as for recent US works, while the Berne minimum is life plus 50. Exceptions also differ, from quotation rules in the EU to fair use in the US.
This is a general overview rather than legal advice; for a specific case, a copyright lawyer is the right person to ask.