Links between issues

Issue links help group multiple issues based on a common theme or view the issue hierarchy.

Tracker has several link types:

Parent issue — Sub-issue
You can use this link type to decompose your issues. Break larger project chunks into standalone issues and sub-issues.
Let's say you need to implement a new feature in your product, which implies resolving multiple smaller issues. For such cases, you can create a parent issue of the “New feautre” type and link your sub-issues to it.
Related to
Use this link type to reference other issues with a common theme.
Depends on — Blocks
Use this link type if a certain issue can only be worked on once another issue is completed. For instance, a new app feature that can only enter development once the interface has been designed.
Duplicated by — Duplicates
Use this link type to group issues that describe the same task. As an example, this link should be used if you created multiple “Bug”-type issues that describe the same problem.
Epic for — Sub-epic
Use this link type to decompose tasks if you're working with Scrum.

You can view and edit the link list on the issue page.