An epic captures a large body of work. It is essentially a large user story that can be broken down into a number of smaller stories. In Scrum projects, for instance, it may take several sprints to complete an epic. You might use epics to capture broader themes in a release, e.g. performance-related work for Scrum projects, and quarterly audit-related work for Kanban projects.
Jira
Leading agile projects - Atlassian Documentation
Starting a new project
Starting a new project - Atlassian Documentation
Building a backlog
Using your Scrum backlog - Atlassian Documentation
Issue Types
Issue types - Atlassian Documentation
Estimate stories - By default, the Story Points field is only available to issues of type 'story' or 'epic'.
Configuring estimation and tracking - Atlassian Documentation
Estimating an issue - Atlassian Documentation
Planning a version
Planning a version - Atlassian Documentation
Version
Configuring versions in a Scrum project - Atlassian Documentation
Epic
An epic captures a large body of work. It is essentially a large user story that can be broken down into a number of smaller stories. In Scrum projects, for instance, it may take several sprints to complete an epic. You might use epics to capture broader themes in a release, e.g. performance-related work for Scrum projects, and quarterly audit-related work for Kanban projects.
Working with epics - Atlassian Documentation
Managing epics in a Scrum project - Atlassian Documentation
Getting to work
Running sprints in a Scrum project - Atlassian Documentation
Releasing a version
Reporting