High quality links and low quality links
Your backlinks don’t have to be perfect, but if they fulfill a good part of the following criteria, then you can be sure that they can help your site.
- Anchor Text
The quality of your backlink will increase if the words that form the clickable text of the link are the same as, or similar to, the words that you’re trying to improve your rankings for. However, make sure that you are not using the same anchor text everywhere, otherwise you dilute its value.
The page that is getting the backlink must be a trusworthy site (looks legitimate, no spam), it should be relevant to your industry or business, and if it is a well-known site, all the better.
If the link was extremely easy to obtain, then chances are many others have obtained it before you, thus diluting it’s value.