What is FSD?

FSD stands for Full Self Driving. The term is famously associated with US-based electric vehicle company, Tesla.

So, you have FSD software and FSD cars. 

The Verge reported that Tesla released their FSD Beta software to a select number of users. The report says that the Beta release "...will enable drivers to access Autopilot’s partially automated driver assist system on city streets. The early access program is used as a testing platform to help iron out software bugs."

Meanwhile Elon Musk had tweeted that he "Will be extremely slow & cautious, as it should."