For Google, let say, because everyone loves them some Google. I am just running out of ways to backlink, and my mind is done with all these articles about it.
Can I say I hate them so much? Haha, it just gets harder and my head can't keep up..but it could be the caffeine rush from trying to figure things out.
It doesn't matter how many updates Google rolls out, backlinks are always going to be important. The only thing that keeps changing is the type of backlinks that you need. These days, it's very much quality over quantity. Ten backlinks from reputable sources are worth more than a thousand of the spam variety.
Back-linking was the original idea based on how librarians classified scholarly articles. The more cites your paper has and the more important the people who are citing it, the more important the paper is. It is what you got since the rest is a secret.