<s>
A	O
grammar	B-Application
checker	I-Application
,	O
in	O
computing	O
terms	O
,	O
is	O
a	O
program	B-Application
,	O
or	O
part	O
of	O
a	O
program	B-Application
,	O
that	O
attempts	O
to	O
verify	O
written	O
text	O
for	O
grammatical	O
correctness	O
.	O
</s>
<s>
Grammar	B-Application
checkers	I-Application
are	O
most	O
often	O
implemented	O
as	O
a	O
feature	O
of	O
a	O
larger	O
program	B-Application
,	O
such	O
as	O
a	O
word	B-General_Concept
processor	I-General_Concept
,	O
but	O
are	O
also	O
available	O
as	O
a	O
stand-alone	O
application	B-Application
that	O
can	O
be	O
activated	O
from	O
within	O
programs	O
that	O
work	O
with	O
editable	O
text	O
.	O
</s>
<s>
The	O
implementation	O
of	O
a	O
grammar	B-Application
checker	I-Application
makes	O
use	O
of	O
natural	B-Language
language	I-Language
processing	I-Language
.	O
</s>
<s>
The	O
earliest	O
"	O
grammar	B-Application
checkers	I-Application
"	O
were	O
programs	O
that	O
checked	O
for	O
punctuation	O
and	O
style	O
inconsistencies	O
,	O
rather	O
than	O
a	O
complete	O
range	O
of	O
possible	O
grammatical	O
errors	O
.	O
</s>
<s>
The	O
first	O
system	O
was	O
called	O
Writer	B-Device
's	I-Device
Workbench	I-Device
,	O
and	O
was	O
a	O
set	O
of	O
writing	O
tools	O
included	O
with	O
Unix	B-Application
systems	I-Application
as	O
far	O
back	O
as	O
the	O
1970s	O
.	O
</s>
<s>
The	O
whole	O
Writer	B-Device
's	I-Device
Workbench	I-Device
package	O
included	O
several	O
separate	O
tools	O
to	O
check	O
for	O
various	O
writing	O
problems	O
.	O
</s>
<s>
Aspen	O
Software	O
of	O
Albuquerque	O
,	O
New	O
Mexico	O
released	O
the	O
earliest	O
version	O
of	O
a	O
diction	O
and	O
style	O
checker	O
for	O
personal	O
computers	O
,	O
Grammatik	B-Application
,	O
in	O
1981	O
.	O
</s>
<s>
Grammatik	B-Application
was	O
first	O
available	O
for	O
a	O
Radio	O
Shack	O
-	O
TRS-80	B-Device
,	O
and	O
soon	O
had	O
versions	O
for	O
CP/M	B-Application
and	O
the	O
IBM	B-Device
PC	I-Device
.	O
</s>
<s>
Reference	O
Software	O
of	O
San	O
Francisco	O
,	O
California	O
,	O
acquired	O
Grammatik	B-Application
in	O
1985	O
.	O
</s>
<s>
Development	O
of	O
Grammatik	B-Application
continued	O
,	O
and	O
it	O
became	O
an	O
actual	O
grammar	B-Application
checker	I-Application
that	O
could	O
detect	O
writing	O
errors	O
beyond	O
simple	O
style	O
checking	O
.	O
</s>
<s>
While	O
all	O
the	O
earliest	O
programs	O
started	O
out	O
as	O
simple	O
diction	O
and	O
style	O
checkers	O
,	O
all	O
eventually	O
added	O
various	O
levels	O
of	O
language	O
processing	O
,	O
and	O
developed	O
some	O
level	O
of	O
true	O
grammar	B-Application
checking	I-Application
capability	O
.	O
</s>
<s>
Until	O
1992	O
,	O
grammar	B-Application
checkers	I-Application
were	O
sold	O
as	O
add-on	O
programs	O
.	O
</s>
<s>
There	O
were	O
a	O
large	O
number	O
of	O
different	O
word	O
processing	O
programs	O
available	O
at	O
that	O
time	O
,	O
with	O
WordPerfect	B-Application
and	O
Microsoft	B-Application
Word	I-Application
the	O
top	O
two	O
in	O
market	O
share	O
.	O
</s>
<s>
In	O
1992	O
,	O
Microsoft	O
decided	O
to	O
add	O
grammar	B-Application
checking	I-Application
as	O
a	O
feature	O
of	O
Word	O
,	O
and	O
licensed	O
CorrecText	O
,	O
a	O
grammar	B-Application
checker	I-Application
from	O
Houghton	O
Mifflin	O
that	O
had	O
not	O
yet	O
been	O
marketed	O
as	O
a	O
standalone	O
product	O
.	O
</s>
<s>
WordPerfect	B-Application
answered	O
Microsoft	O
's	O
move	O
by	O
acquiring	O
Reference	O
Software	O
,	O
and	O
the	O
direct	O
descendant	O
of	O
Grammatik	B-Application
is	O
still	O
included	O
with	O
WordPerfect	B-Application
.	O
</s>
<s>
As	O
of	O
2019	O
,	O
grammar	B-Application
checkers	I-Application
are	O
built	O
into	O
systems	O
like	O
Google	B-Application
Docs	I-Application
and	O
Sapling.ai,	O
browser	O
extensions	O
like	O
Grammarly	B-Operating_System
and	O
Qordoba	B-Application
,	O
desktop	B-Application
applications	I-Application
like	O
Ginger	B-Library
,	O
free	B-License
and	I-License
open-source	I-License
software	I-License
like	O
LanguageTool	B-Operating_System
,	O
and	O
text	O
editor	O
plugins	O
like	O
those	O
available	O
from	O
WebSpellChecker	O
Software	O
.	O
</s>
<s>
This	O
process	O
was	O
based	O
on	O
simple	O
pattern	B-Language
matching	I-Language
.	O
</s>
<s>
The	O
heart	O
of	O
the	O
program	B-Application
was	O
a	O
list	O
of	O
many	O
hundreds	O
or	O
thousands	O
of	O
phrases	O
that	O
are	O
considered	O
poor	O
writing	O
by	O
many	O
experts	O
.	O
</s>
<s>
The	O
checking	O
program	B-Application
would	O
simply	O
break	O
text	O
into	O
sentences	O
,	O
check	O
for	O
any	O
matches	O
in	O
the	O
phrase	O
dictionary	B-Operating_System
,	O
flag	O
suspect	O
phrases	O
and	O
show	O
an	O
alternative	O
.	O
</s>
<s>
True	O
grammar	B-Application
checking	I-Application
is	O
more	O
complex	O
.	O
</s>
<s>
One	O
can	O
write	O
a	O
somewhat	O
complete	O
formal	O
grammar	O
for	O
a	O
natural	O
language	O
,	O
but	O
there	O
are	O
usually	O
so	O
many	O
exceptions	O
in	O
real	O
usage	O
that	O
a	O
formal	O
grammar	O
is	O
of	O
minimal	O
help	O
in	O
writing	O
a	O
grammar	B-Application
checker	I-Application
.	O
</s>
<s>
One	O
of	O
the	O
most	O
important	O
parts	O
of	O
a	O
natural	O
language	O
grammar	B-Application
checker	I-Application
is	O
a	O
dictionary	B-Operating_System
of	O
all	O
the	O
words	O
in	O
the	O
language	O
,	O
along	O
with	O
the	O
part	O
of	O
speech	O
of	O
each	O
word	O
.	O
</s>
<s>
The	O
fact	O
that	O
a	O
natural	O
word	O
may	O
be	O
used	O
as	O
any	O
one	O
of	O
several	O
parts	O
of	O
speech	O
(	O
such	O
as	O
"	O
free	O
"	O
being	O
used	O
as	O
an	O
adjective	O
,	O
adverb	O
,	O
noun	O
,	O
or	O
verb	O
)	O
greatly	O
increases	O
the	O
complexity	O
of	O
any	O
grammar	B-Application
checker	I-Application
.	O
</s>
<s>
A	O
grammar	B-Application
checker	I-Application
will	O
find	O
each	O
sentence	O
in	O
a	O
text	O
,	O
look	O
up	O
each	O
word	O
in	O
the	O
dictionary	B-Operating_System
,	O
and	O
then	O
attempt	O
to	O
parse	B-Language
the	O
sentence	O
into	O
a	O
form	O
that	O
matches	O
a	O
grammar	O
.	O
</s>
<s>
Using	O
various	O
rules	O
,	O
the	O
program	B-Application
can	O
then	O
detect	O
various	O
errors	O
,	O
such	O
as	O
agreement	O
in	O
tense	O
,	O
number	O
,	O
word	O
order	O
,	O
and	O
so	O
on	O
.	O
</s>
<s>
Grammar	B-Application
checkers	I-Application
may	O
attempt	O
to	O
identify	O
passive	O
sentences	O
and	O
suggest	O
an	O
active-voice	O
alternative	O
.	O
</s>
<s>
The	O
software	O
elements	O
required	O
for	O
grammar	B-Application
checking	I-Application
are	O
closely	O
related	O
to	O
some	O
of	O
the	O
development	O
issues	O
that	O
need	O
to	O
be	O
addressed	O
for	O
speech	B-Application
recognition	I-Application
software	I-Application
.	O
</s>
<s>
In	O
voice	O
recognition	O
,	O
parsing	B-Language
can	O
be	O
used	O
to	O
help	O
predict	O
which	O
word	O
is	O
most	O
likely	O
intended	O
,	O
based	O
on	O
part	O
of	O
speech	O
and	O
position	O
in	O
the	O
sentence	O
.	O
</s>
<s>
In	O
grammar	B-Application
checking	I-Application
,	O
the	O
parsing	B-Language
is	O
used	O
to	O
detect	O
words	O
that	O
fail	O
to	O
follow	O
accepted	O
grammar	O
usage	O
.	O
</s>
<s>
Grammar	B-Application
checkers	I-Application
are	O
considered	O
as	O
a	O
type	O
of	O
foreign	B-Application
language	I-Application
writing	I-Application
aid	I-Application
which	O
non-native	O
speakers	O
can	O
use	O
to	O
proofread	O
their	O
writings	O
as	O
such	O
programs	O
endeavor	O
to	O
identify	O
syntactical	O
errors	O
.	O
</s>
<s>
However	O
,	O
as	O
with	O
other	O
computerized	O
writing	O
aids	O
such	O
as	O
spell	B-Application
checkers	I-Application
,	O
popular	O
grammar	B-Application
checkers	I-Application
are	O
often	O
criticized	O
when	O
they	O
fail	O
to	O
spot	O
errors	O
and	O
incorrectly	O
flag	O
correct	O
text	O
as	O
erroneous	O
.	O
</s>
<s>
The	O
linguist	O
Geoffrey	O
K	O
.	O
Pullum	O
argued	O
in	O
2007	O
that	O
they	O
were	O
generally	O
so	O
inaccurate	O
as	O
to	O
do	O
more	O
harm	O
than	O
good	O
:	O
"	O
for	O
the	O
most	O
part	O
,	O
accepting	O
the	O
advice	O
of	O
a	O
computer	O
grammar	B-Application
checker	I-Application
on	O
your	O
prose	O
will	O
make	O
it	O
much	O
worse	O
,	O
sometimes	O
hilariously	O
incoherent.	O
"	O
</s>
