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 with few differences. Generally speaking, there are four steps when importing data into JIRA that are as follows:
Select your source data. For example, if you are importing from CSV, it will select the CSV file. If you are importing from Bugzilla, it will provide Bugzilla database details.
Select a destination project where imported issues will go into. 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.