Radar

Radar was Apple's internal bug tracking system. was is maintained by Apple employees for development tracking, from bugs to tasks to enhancements to features to problems to issues with IT.

Usage
Apple's Radar system was open to registered members of the Apple Developer program who could use it to file bug reports or enhancement requests. Although Radar was reportedly versatile when used by Apple employees, its data was not openly accessible to users outside of the company. The constant request to "file a radar" were often followed by weeks or years without an any indication that anyone had ever acknowledged or even read about the issue. This led to the perception of the Radar system being a “black hole”.

Criticism
Users had no way of knowing if an issue had already been reported, so it was common to receive a reply that it was a duplicate of another issue. However, the user would not be able to find out whether the issue was ever resolved. Developer Tim Burks responded by creating an open source database called Open Radar which could also accept radar submissions, but allowed the bug reports to be openly searchable.

iOS App
The app is installed through SwitchBoard for confidential use within Apple. It can be accessed by typing in the address bar of Safari on an iPhone, iPad, or iPod touch. If Radar is not installed, the user would be redirected to Apple's debugging web portal, Apple Bug Reporter (now Feedback Assistant), which is open to consumers, developers, and businesses to report bugs during beta testing of Apple products.

Stickers
Radar also contains a set of iMessage stickers in its iOS App.

Trivia
One of the stickers includes the meme.

Discontinuation
At the 2019 Worldwide Developers Conference in June, Apple replaced Radar with a native developer app of Feedback Assistant for iOS 12.4 and macOS Catalina or later. However, the prefix is still used for individual bug reports. With the announcement of iOS 14 and macOS Big Sur at the 2020 Worldwide Developers Conference, Apple introduced "Teams for Feedback Assistant", which allows enterprise developer groups to collaborate on feedback and check one another's bug reports on a common project.

Articles

 * 5 Tips for Filing Radars by Matthew Bischoff at Lickability (2019-02-07)
 * Bug Reporting by Mattt at NSHipster (2018-07-16)