This is typically referred to as the "synchronization" functionality, which is bi-directional. This allows you to create an association between a JIRA issue and any Salesforce.com object (e.g. Case, Account, Solution, Opportunity, custom objects, etc.).
Once associated, you can then "share" information across the two systems such that when the Salesforce.com object is updated, the JIRA issue is updated as well. Likewise, when the JIRA issue is updated, the Salesforce.com object is updated. You are able to control what fields are updated in each system with our flexible Mapping Configurations. In addition, comments are also automatically synchronized across the two systems.
This synchronization can be used in conjunction with the Remote Object Link option to create associations with multiple Salesforce.com object types.
For example, you can use the Remote System Reference to link the issue with a Salesforce.com Case and then configure additional Remote Object Link references for the Account, Contact and Owner. The associated values can be mapped using our Mapping Configurations, and by doing so, the system will automatically pull across the Account, Contact and Owner of the Case when the issue is created or synchronized.
Automatically updates the other system based on a flexible set of Mapping Configurations, so data is editable in both systems
Automatically create and update comments between systems (the automatic creation can be disabled in the configurations so that you can selectively push comments from JIRA to Salesforce.com)
You can still access the mapped data in the event the other system is unavailable temporarily (e.g. during scheduled maintenance)
Can be used in conjunction with Remote Object Link to establish links to multiple Salesforce.com object types
You should use this if you want to share information between the systems so that it is updateable from both systems.
For example, you can map the JIRA issue Priority field to the Salesforce.com Case Priority field. When the JIRA issue's priority is updated, the Salesforce.com Case's priority is automatically updated to match.
Likewise, if you would like comments in JIRA to appear in Salesforce.com (we currently support comments on Case and Idea objects) and vice versa, this is the recommended approach.