iATS Payments is a payment processor company that specializes in services for non-profits. iATS Payments has been supported for CiviCRM with a payment processor plugin that was originally written (by Alan Dixon) in 2007.
Since 2013, Blackfly Solutions (Alan and Karin) have maintained a rewritten, official version of the extension, hosted on github
The civicrm extension "home" is hosted on civicrm.org