Is a footer backlink efficient?
A commonly accepted rule would be that footer links are less efficient than other links.
The footer being located at the bottom of the page common to all the pages of the site, in opposition to the header which is the highest area of the website where you usually find the logo.
First of all, you must know that it is perfectly possible to display the content of the footer at the beginning of the HTML source code.
Indeed, thanks to CSS styles, the order of the elements displayed on the screen can be very different from the order of the content visited by robots. The aforementioned used to read the HTML code in a complete linear way in opposition to the browser that will interpret the HTML code, JS and CSS.
A footer link can therefore be located very high in the source code.
It is then important to distinguish the structural zones (Header, navigation menu, Sidebar...) from the contextual zones: where the content specific to each page is most often displayed.
It would make sense that a link located in a contextual area would receive better treatment than a link placed in a structural area.
Anyways, this potential evaluation mechanism would not tear apart the popularity broadcasted by a footer link.
A footer link then still remains good to take in most cases. The most important is to not systematize or fill your links footer when it is not relevant.