Backlinks are links that point from another website (link source) to a specific website (link destination). This particular website can be a website, a web page or a web directory.

Backlinks are similar to citations. The number, quality and relevance of backlinks to a web page are among the factors that search engines like Google evaluate to estimate the importance of that page.

PageRank calculates a link score for each web page based on how all web pages are connected to each other, and is one of the variables that Google Search uses to determine how high a web page should rank in search results.

This weighting of backlinks is similar to the citation analysis of books, scientific articles and academic journals. Also, a Topical PageRank has been researched and implemented, which gives more weight to the backlinks received from the page with the same topic as the target page.
Some other words for backlink are incoming link, inbound link, inbound link, inward link and citation.

Backlinks are provided on wikis, but usually only within the scope of the wiki itself and when enabled by the database backend. MediaWiki specifically provides a "what links here" tool, some older wikis, notably the first WikiWikiWeb, did display backlinks in the page title.

A link Search engines often use the number of backlinks of a website as one of the most important factors to determine the search engine ranking, popularity and importance of that website.
A link has high search engine ranking importance and is considered as a vital parameter in online business and the conversion rate of visitors to any website, especially when it comes to online shopping. Blog commenting, guest blogging, article submissions, press release distribution, social media participation, and forum posting can all be used to increase backlinks.

Websites often use SEO techniques to increase the number of backlinks pointing to their website. Some methods are accessible to everyone while others, like link baiting, require a lot of planning and marketing to work.

There are also paid techniques to increase the number of backlinks to a target site. For example, private blog networks can be used to buy backlinks. It was estimated that the average cost of buying a link in 2019, when marketing blogs were excluded from the calculation, was $291.55 and $391.55.
Several factors determine the value of a backlink. Backlinks from reputable sites on a specific topic are very valuable. If both sites and pages have relevant content
A backlink is considered relevant and is believed to have a strong impact on the search engine ranking of the web page giving the backlink. A backlink represents a positive "written vote" for the receiving web page from another giving web page.
Another important factor is the backlink anchor text. Anchor text is the descriptive tag of a hyperlink that appears on a web page. Search engine bots (ie spiders, crawlers, etc.) examine anchor text to assess how relevant it is to the content of a web page.
Backlinks can be generated through submissions, such as directory submissions, forum submissions, social bookmarking, business listings, blog submissions, etc. The match between anchor text and web page content is highly weighted in a web page's search engine results page (SERP) ranking for any given keyword query by a search engine user.
A link Changes in the algorithms that generate search engine rankings can focus more on relevance to a specific topic. While some backlinks may come from sources with very valuable metrics, they may also be unrelated to the consumer's query or interest.

An example of this would be a link from a popular shoe blog (with valuable metrics) to a site selling vintage sharpeners. While this link looks valuable, it offers little in the way of communication to the consumer.