<s>
GraphQL	B-Language
is	O
an	O
open-source	O
data	O
query	B-Language
language	I-Language
and	O
data	B-Language
manipulation	I-Language
language	I-Language
for	O
APIs	B-General_Concept
,	O
and	O
a	O
query	O
runtime	O
engine	O
.	O
</s>
<s>
Facebook	B-Application
(	O
now	O
Meta	O
)	O
started	O
GraphQL	B-Language
development	O
in	O
2012	O
and	O
released	O
it	O
in	O
2015	O
.	O
</s>
<s>
GraphQL	B-Language
was	O
moved	O
on	O
7	O
November	O
2018	O
to	O
the	O
newly	O
established	O
GraphQL	B-Language
Foundation	O
,	O
hosted	O
by	O
the	O
non-profit	O
Linux	B-Operating_System
Foundation	I-Operating_System
.	O
</s>
<s>
On	O
9	O
February	O
2018	O
,	O
the	O
GraphQL	B-Language
Schema	O
Definition	O
Language	O
(	O
SDL	O
)	O
became	O
part	O
of	O
the	O
specification	O
.	O
</s>
<s>
GraphQL	B-Language
provides	O
a	O
web	B-General_Concept
API	I-General_Concept
approach	O
in	O
which	O
clients	O
define	O
the	O
structure	O
of	O
the	O
data	O
to	O
be	O
returned	O
by	O
the	O
server	O
.	O
</s>
<s>
This	O
can	O
impede	O
web	B-Protocol
caching	I-Protocol
of	O
query	O
results	O
.	O
</s>
<s>
GraphQL	B-Language
does	O
not	O
provide	O
a	O
full-fledged	O
graph	B-Application
query	B-Language
language	I-Language
such	O
as	O
SPARQL	B-Language
,	O
or	O
even	O
in	O
dialects	B-Language
of	I-Language
SQL	I-Language
that	O
support	O
transitive	O
closure	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
GraphQL	B-Language
interface	O
that	O
reports	O
the	O
parents	O
of	O
an	O
individual	O
cannot	O
return	O
,	O
in	O
a	O
single	O
query	O
,	O
the	O
set	O
of	O
all	O
their	O
ancestors	O
.	O
</s>
<s>
GraphQL	B-Language
consists	O
of	O
a	O
type	O
system	O
,	O
query	B-Language
language	I-Language
and	O
execution	O
semantics	O
,	O
static	O
validation	O
,	O
and	O
type	B-Application
introspection	I-Application
.	O
</s>
<s>
It	O
supports	O
reading	O
,	O
writing	O
(	O
mutating	O
)	O
,	O
and	O
subscribing	O
to	O
changes	O
to	O
data	O
(	O
realtime	O
updates	O
–	O
most	O
commonly	O
implemented	O
using	O
Websockets	B-Protocol
)	O
.	O
</s>
<s>
GraphQL	B-Language
servers	O
are	O
available	O
for	O
multiple	O
languages	O
.	O
</s>
<s>
The	O
result	O
of	O
a	O
single	O
query	O
is	O
returned	O
in	O
JSON	B-General_Concept
format	O
.	O
</s>
<s>
POST	B-Protocol
request	I-Protocol
:	O
</s>
<s>
GraphQL	B-Language
APIs	B-General_Concept
can	O
be	O
tested	O
manually	O
or	O
with	O
automated	O
tools	O
issuing	O
GraphQL	B-Language
requests	O
and	O
verifying	O
the	O
correctness	O
of	O
the	O
results	O
.	O
</s>
