Sitewide links are those which appear on every page of your site. These generally show up in either the menu/navigational bar or section of your site, in the header section, or in the footer section. Sitewide links are either going to be internal (pointing to pages on that same site) or external (pointing to pages on other websites.
Are Sitewide Links Bad For SEO
An example would be footer links like those right on this site:
Internal sitewide links are completely fine and are used by most websites because they make for a user friendly experience. Furthermore, they’re not being used to spread link juice to other sites, or in other words they’re not being used to affect Google or other search engines with the purpose of improving someone’s rankings artificially. All of the traffic and link juice stays and spreads around your site with internal sitewide links and helps your audience navigate your site more effectively.
External sitewide links are where it begins to get hairy, because you’re now including a link to another website on every single page of your site. In today’s anal retentive world of search engines, that looks suspicious to say the least.
Note that the following is my own personal conjecture because Google has never come out and made it explicitly clear one way or the other.
If you make the link NoFollow, adding the rel=”nofollow” tag to the link, it won’t pass any influence/link juice to other sites, then you know that you won’t have any issues down the road because you’re not trying to pass influence, just a helpful link for the traffic purposes. Nothing wrong with this at all, so if you’re in doubt, go for NoFollow.
Conversely, if you leave the link as a DoFollow, and particularly if that link’s anchor text is the keyword you’re targeting on that linking to page, you may get dinged by Google someday if you haven’t already. If you add more sites to the profile, it gets even more dangerous.
Ultimately it’s very subjective with a lot of shades of gray as opposed to a yes or no answer. If your anchor text is more of a branding keyword and you’re only doing it from one site to another, then that’s not as big of an issue.
If you really just want your link to function as a way to send visitors from one site to another, make it NoFollow. Many webmasters aren’t concerned with SEO when it comes to sitewide links; they may not care if their site ranks well, they just want the traffic from one site to go to the other, and NoFollow will accomplish that just fine.