Image provided by Pixabay under the CC0 license

The most immersive virtual reality experiences often use a PC , VR headset,  and software.   

The latest version of some headsets can be used without an accompanying PC but a
PC will be needed to update the headset software.   Handheld controllers can also be added
for additional control over the virtual environment.   These VR devices can track a user's movement,  called "positional tracking",  within a space - a feature not available when using VR apps and a smartphone.

The healthcare industry is developing applications and uses for these types of devices. 
Some areas of high development are PSTD treatment,  anxiety disorder  treatment, and pain management.