What is 'private tester'?

[B@ng]

I see some saying beta version under trial and testing under trial.
what are private tester?
is some part of legoins override done and played by testers?
can i knw how it is?
plzz i m vry interesterd

 

[SeymourGore]

Private testers work with the Legions: Overdrive developers to squash bugs, early test builds, etc. More information can be found on the blog.