Anyone who’s gotten their feet wet in search engine optimization waters knows that there are two kinds of backlinks: good ones and bad ones. In those endless lists about how to start or improve your SEO strategy, you’re told to get rid of your bad links and build your good link profile. But what does that even mean? What qualifies as a bad link?

2015 was a difficult year for link building. Changes to Google’s algorithm meant that some types of links that might have been alright before, were now just as bad as the garbage links. Some people heard Google’s spokesperson say that link building was a bad strategy and abandoned the practice altogether, despite the fact that it is still one of the site’s biggest factors when determining page ranking.

The trend is moving away from “building” links, to “earning” links—that’s all that has really changed over the last year. It’s safer, more natural, and puts the emphasis back on the quality of the content being linked to. But it can still be difficult to determine whether or not that link, even if earned naturally, is one you want in your profile. Here’s what you want to look out for:

1. The Link is Posted On a Website With Little to No Authority or On a Sketchy Domain.

This is probably the biggest red flag when it comes to links. The whole point of earning links is to steal authority and page rank juice from websites that already have plenty. If the link is one a website that has low authority rankings and/or the domain is a little sketchy, it isn’t just not good, it can actually damage your page ranking. One or two won’t kill you, but hundreds will.

2. The Link is Inserted Into Content That is Irrelevant to the Link.

What does this mean? It means that a link to your blog post about the best kinds of tuna is on a webpage that sells shoes. That website might have great authority, but if the content of that page has nothing to do with the content of yours, that link is essentially useless. The links should be very connected to both the context of the page.

3. You Exchanged Links.

It sounds like a good idea: you know someone who owns a website with a context similar to yours—why not exchange links? Because Google said so. It doesn’t like link swaps and if it thinks that you’ve done one, it might actually downgrade the authority of your domain. Again, exchanging one link isn’t that big of a deal, especially if you really think that one link will be valuable to page visitors and/or readers, but more than a few is going to be a red flag.

4. The Link is Isolated From the Content.

You can’t just tack a link at the end of a well-trafficked page and call it good. You also cannot just post a link as a comment on a blog or forum. Google’s algorithm really hates these two things, largely because it makes your link look like spam. People are not likely to click on a link that has no introduction and seemingly no purpose, and because people won’t click on it, Google doesn’t see any value in those links.

5. Your Anchor Text is Your Keyword.

This used to be very important in SEO, and especially for link building. Today, it makes your link look like spam. This is one of the fastest ways to earn a penalty. If your anchor text is an exact match for your keyword, you are likely going to not only not see any value in that link, but also see your page ranking start to drop. There’s no telling why Google hates this practice so much—they just do, so don’t do it and if you have any links in your link profile like this, get rid of them as soon as possible.

6. The Link Appears Too Often on the Same Website.

If this occurs, it looks like that website is being spammed with your link. In this case, more is not better. You can have different links to different pages or posts on the same domain, but repeating the same link over and over does not look good. It’s more important to have lots of different domains leading back to your website than it is to have a lot of links on one domain.

Uses these six criteria to go through your link profile and eliminate the ones that fall into the bad category. Then, start working on “earning” links, through providing excellent content, rather than “building” them.