What are Backlinks?
Backlinks (same as inbound links) are links to a particular web page or resource from other web pages. Backlinks refer to the incoming links only. Links from a page are called outgoing links (but at the same time, they are backlinks for the linked pages).
The quality, quantity, relevance, authority, and anchor text of the backlinks are one of the many ranking factors for Google. In fact, Google openly says that content and links pointing to a website are the most important ranking factors.
The process of increasing the number and quality of backlinks to a webpage or a website is called link-building.