It is not one of Wikipedia's policies or guidelines; rather, its purpose is to explain certain aspects of Wikipedia:Manual of Style/Linking. It may reflect differing levels of consensus and vetting.
Internal links tie Wikipedia together and help readers learn more about a topic.
Link to relevant pages that aid understanding of the subject, and generally:
DO:
Check that your link points to the intended target
Use piping to fit link text into prose
Make link targets clear from context
Link to sections of pages where appropriate
Add red links that would make useful articles
Create redirects from sub-topics or alternate titles
Link to obscure wordsinWiktionary
Link to pages on sister projects where relevant
DON'T:
Don't link to common words, dates, or units
Don't link to disambiguation pages in articles
Don't link to user, project, draft, or talk pages in articles
Don't link to unexpected targets
Don't put external links in article prose
Don't put links in section headings
Don't change the color of links
Don't use action buttons for navigation
Encyclopedia content
Collaboration
