Back links and algorithm

A set of return links, which are also called inbound links, or backlinks, indicates the popularity of the site and its audience. Matt Cutts was the Google Webspam team leader who most spoke to the media about the positioning algorithm. He tells us in an interview published on the Stonetemple website on October 8, 2007:

"Of course, I would like to say that connections are the first thing we are now considering in terms of reputation."

Variable quality of incoming links

According to Matt Cutts, a qualitative connection has the following characteristics:

It must have been given voluntarily.
This is an editorial link, in the text and to supplement the text.
Relevant: in connection with the topic of the article
He has a clear anchor that says what we're pointing to.
He's pretty well trained.
It has no fireworks that alter its nature.
The link is made because you want to tell your visitors about something.

Links to football

These are links that are requested by those who provide site elements such as templates for Wordpress. The author wants his site to have a link embedded in the template. Or links to friendly sites.

These links are subject to the general law, if they are not relevant, that they have nothing to do with the content of the site, they have no value. Since October 2012, the Guideline Webmaster has banned links in football from cobblers. They are considered unnatural and are part of a network of connections.

Mutual relations

Previously, Google did not advise mutual links. Then his notification was finalized: he does not advise excessive mutual ties. But what does being excessive mean?
If links are not natural and not relevant, if you request a back link when creating a link to a site, these mutual links are considered excessive.
They are not there if they are useful to visitors.

Reference: Matt Cutt interview on 16 July 2008.

List of links prohibited by Google

In Webmaster Guidelines, some types of links are considered unnatural and can cause damage to the site:

Too many links between sites. This "too much" is not specified, but if there are more mutual connections than spontaneous, then this is certainly too much.
Links in non-content articles. These are, as a rule, paid connections in fact, but the principle in itself is insurmountable.
Link to a directory or low-quality bookmark sites. Under low quality, it is assumed that these are sites that have few visits, often the same descriptions.
Automated links.
Links to all pages. This is a recent addition to the list, if they are found too often it is fined.
Keyword forum captions. Nothing is less natural, as these links are created by the webmaster itself. In general, self-promotion is punished.
Links in forums. If they are not included in the text associated with a linked site, they are considered spam and carry penalties for the linked site. This mainly applies to links in profiles or signed links.

But these connections are not fined if they are in nofollow .

JavaScript Links

This is known to have been confirmed by Matt Cutts, a Google spokesperson, when it comes to link questions:
JavaScript links are used to detect and index pages by search engines. They are treated as HTML links and can pass PageRank. If they are easy to interpret - after all, Google can execute JavaScript code - they are counted as <a> tags. A JavaScript link usually has the following form:

<span onClick="location.replace('http://www.example.com/')" />Libellé</span>

or with image:

<img src="image.jpg" onClick="location.replace('http://www.example.com/')" />

Then it's easy to find these links for a search engine. But you can write JavaScript code that makes the URL invisible to the engines.

Do I need to disavow backlinks?

There was a time when you wanted maximum backlinks on your site, not caring about their quality, but after Penguin Update, which fines the site for exceeding bad links, the trend turned upside down: webmasters absolutely want to remove unwanted links to their site. An unwanted link refers to links to pages with questionable content, or to directories without visitors next to sites not related to yours, or paid links.
So after Penguin, a tool became indispensable - to allow the webmaster to remove (virtually) links to his site. Now this has been done, since October 16, 2012 it has been included in the Google Webmaster Tools.
Not everyone uses this tool: only those sites that have been punished by these bad links should resort to it.

If you are a site webmaster, you can find out about incoming links through Google Webmaster Tools or from Bing Webmaster Tools. Otherwise, you can find other tools in the Webmaster section.