What is the TLD (Top Level Domain) of a domain and why is it important in your backlink strategy?

Surely you've ever noticed the endings of the domains you visit on the internet (.com, .es, .org...) and you've asked yourself: Does that part of the domain really matter? Yes, that part is called TLD (Top Level Domain), and although it seems a little small, it plays a key role in your SEO strategy, especially when you are planning link building campaigns.