Want to create a custom field for user

[sunil kumar]

1. I want to create a custom field like 'Text field', which need to be associated to the user.

Note: I know that custom fields can be created for issues, but that is not helping in associating the custom field with user.

[Joe Pitt]

Do you mean a field associated with the user profile or a field in an issue associated to a user? 

Out of the box you can't do either. 

[sunil kumar]

Field associated with the user profile, like a extra field to describe details in user profile page.

[Joe Pitt]

There may be a plugin. Look in the marketplace

[sunil kumar]

I have a requirement, like I have a external application, which has an unique identification ID, that I want to store in the user information in Jira, how is it possible to associate that unique identification ID of another system.

[Joe Pitt]

As I said, look for a plugin. JIRA doesn't allow that out of the box