JIRA supports importing data directly from many popular issue-tracking systems, such as Bugzilla, GitHub, and Trac. All the importers have a wizard-driven interface, guiding you through a series of steps. These steps are mostly identical but have a few differences. Generally speaking, there are four steps when importing data into JIRA as follows:
Select your source data. For example, if you are importing from CSV, it will select a CSV file. If you are importing from Bugzilla, it will provide Bugzilla database details.
Select a destination project where the imported issues will go. This can be an existing project or a new project created on-the-fly.
Map old system fields to JIRA fields.
Map old system field values to JIRA field values. This is usually required for select-based fields, such as the priority field, or select list custom fields.