What is an instance in JIRa stands for? Every single user or a project with n number of users?

[Mahalakshmi Sivasamy]

What is an instance in JIRa stands for? Every single user or a project with n number of users?

[Nic Brough -Adaptavist-]

We usually use the word "instance" to talk about a single Jira installation.

Imagine I download Jira.  I take the installation files and copy them to three computers and run them.  At the end of the installation, I have three separate "instances" of Jira.  Three separate urls that they run on and isolated data-sets.

Now imagine that I convert them to a Data Centre installation.  Each instance becomes a node in the DC.  I now only have one "instance" because there's only one url and one collection of projects, users, etc.