A virtual keyboard is a form factor of the keyboard delivered logically through a software interface.
It is used as an alternative to a traditional keyboard and can be accessed through various interfaces.
A virtual keyboard may also be called an on-screen keyboard or soft keyboard.
Techopedia explains Virtual Keyboard
The virtual keyboard was initially designed to provide an on-screen instance of the keyboard for users with disabilities or a malfunctioning physical keyboard. User simply point and click (or on a touchscreen, touch) the visible keys. Another form of the virtual keyboard is the optical projected and detected keyboard. The optical projected keyboard projects a diagram of a keyboard on any physical plane. The detector captures the user's movements on the optical surface to identify his or her keyboard inputs.