What is a sub-user account?

I am reviewing the upgrade options and want to understand what a sub-user account is.  Is it the ability for form-filler outers to have access to their accounts and make updates as needed (longitudinal)?  Or is it the ability for multiple people to edit and distribute the surveys?

That is explained on this page http://www.jotform.com/help/232-How-to-Share-Forms-with-a-Sub-Account-User.

Sub-account is basically a separate account where you share your forms with permissions like the sub-user can edit your form or view its submissions data. Sub-account is usually owned and maintained by the master account.

If you have further questions, let us know.