<s>
Glk	B-Device
is	O
a	O
portable	O
application	B-Application
programming	I-Application
interface	I-Application
(	O
API	B-Application
)	O
created	O
by	O
Andrew	O
Plotkin	O
for	O
use	O
by	O
programs	O
with	O
a	O
text	O
interface	B-Application
;	O
these	O
programs	O
mostly	O
include	O
interactive	O
fiction	O
(	O
IF	O
)	O
interpreters	B-Application
for	O
Z-machine	O
,	O
TADS	B-Application
,	O
Glulx	O
,	O
and	O
Hugo	O
games	O
,	O
and	O
IF	O
games	O
written	O
in	O
more	O
obscure	O
file	O
formats	O
such	O
as	O
those	O
used	O
by	O
Level	O
9	O
Computing	O
and	O
Magnetic	O
Scrolls	O
.	O
</s>
<s>
The	O
Glk	B-Device
API	B-Application
specification	O
describes	O
facilities	O
for	O
input	B-General_Concept
,	O
output	O
,	O
text	O
formatting	O
,	O
graphics	O
,	O
sound	O
,	O
and	O
file	O
I/O	B-General_Concept
.	O
</s>
<s>
Glk	B-Device
does	O
not	O
describe	O
a	O
virtual	B-Architecture
machine	I-Architecture
.	O
</s>
<s>
Glulx	O
is	O
a	O
virtual	B-Architecture
machine	I-Architecture
designed	O
to	O
be	O
implemented	O
using	O
the	O
Glk	B-Device
functions	O
,	O
and	O
Glulxe	O
is	O
an	O
interpreter	B-Application
for	O
Glulx	O
.	O
</s>
<s>
Interpreters	B-Application
for	O
other	O
virtual	B-Architecture
machines	I-Architecture
may	O
use	O
Glk	B-Device
while	O
being	O
unrelated	O
to	O
Glulx	O
:	O
for	O
example	O
,	O
Nitfol	O
is	O
an	O
interpreter	B-Application
for	O
the	O
Z-Machine	O
that	O
uses	O
Glk	B-Device
.	O
</s>
<s>
The	O
Glk	B-Device
API	B-Application
has	O
many	O
implementations	O
,	O
including	O
GlkTerm	O
,	O
ScummVM	B-Device
's	O
Glk	B-Device
,	O
WindowsGlk	O
,	O
XGlk	O
.	O
</s>
<s>
The	O
existence	O
of	O
the	O
Glk	B-Device
API	B-Application
has	O
made	O
possible	O
the	O
creation	O
of	O
"	O
universal	O
translator	O
"	O
IF	O
interpreters	B-Application
,	O
programs	O
such	O
as	O
Gargoyle	O
and	O
Spatterlight	O
which	O
can	O
run	O
all	O
popular	O
IF	O
formats	O
and	O
almost	O
all	O
of	O
the	O
more	O
obscure	O
ones	O
.	O
</s>
<s>
Such	O
programs	O
are	O
very	O
useful	O
for	O
newcomers	O
to	O
the	O
medium	O
who	O
are	O
unsure	O
of	O
which	O
interpreter	B-Application
to	O
choose	O
,	O
and	O
to	O
experienced	O
players	O
who	O
may	O
possess	O
games	O
in	O
a	O
variety	O
of	O
formats	O
.	O
</s>
