General Best Practices

If you are setting up a transition between pages or content on your existing site – whether clicking on a hyperlink, a button, a menu option, a sidebar – you don't want to open in a new tab for content within the same website unless there is a really compelling reason to do so. Users may get annoyed by the unnecessary opening of multiple browser tabs.

That being said, there may be specific reasons to open something in a new browser tab:

1. The user needs to see content simultaneously, such as when they are watching a video/livestream in one tab and need to open an accompanying document or read about what they are watching in another tab. 
2. The content being clicked on is a PDF. Some PDF readers don't allow backwards navigation, so we don't want the user to lose their place on the site.
3. If you are sending users off the site to another site, then you want to open the new site link in a new tab, again – so they don't lose their place our your site.