What does GI stand for?

It’s a term I hear about a lot when 3D assets are mentioned but I don’t know what this acronym stands for.
(See post below for answer.)

GI stands for Global Illumination. According to the official online Unity manual:

Global Illumination (GI) is a system
that models how light is bounced off
of surfaces onto other surfaces
(indirect light) rather than being
limited to just the light that hits a
surface directly from a light source
(direct light). Modelling indirect
lighting allows for effects that make
the virtual world seem more realistic
and connected, since objects affect
each other’s appearance. One classic
example is ‘color bleeding’ where, for
example, sunlight hitting a red sofa
will cause red light to be bounced
onto the wall behind it. Another is
when sunlight hits the floor at the
opening of a cave and bounces around
inside so the inner parts of the cave
are illuminated too.

Here’s an example image, also from the same page: