Backlinks are incoming hyperlinks from a page on one website to a different website. It is widely believed that backlinks signal greater authority to search engines and are therefore factored into search rankings. They are also a good KPI for measuring the quality of your content marketing.
It is important to have backlinks from quality sites, and those backlinks should be contextual. If, for example, you have a site about fish, and you are creating links from other niche sites about monkeys, these links will be of no use. Your goal should be to get links from authoritative and relevant sites.