<s>
NonVisual	B-Language
Desktop	I-Language
Access	I-Language
(	O
NVDA	O
)	O
is	O
a	O
free	B-License
and	I-License
open-source	I-License
,	O
portable	O
screen	O
reader	O
for	O
Microsoft	B-Application
Windows	I-Application
.	O
</s>
<s>
NVDA	O
is	O
programmed	O
in	O
Python	B-Language
.	O
</s>
<s>
It	O
currently	O
works	O
exclusively	O
with	O
accessibility	O
APIs	B-Application
such	O
as	O
UI	B-Application
Automation	I-Application
,	O
Microsoft	O
Active	O
Accessibility	O
,	O
IAccessible2	B-Application
and	O
the	O
Java	B-Language
Access	I-Language
Bridge	I-Language
,	O
rather	O
than	O
using	O
specialized	O
video	O
drivers	O
to	O
"	O
intercept	O
"	O
and	O
interpret	O
visual	O
information	O
.	O
</s>
<s>
It	O
is	O
licensed	O
under	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
version	O
2	O
.	O
</s>
<s>
Concerned	O
by	O
the	O
high	O
cost	O
of	O
commercial	O
screen	O
readers	O
,	O
In	O
April	O
2006	O
,	O
Michael	O
Curran	O
began	O
writing	O
a	O
Python-based	O
screen	O
reader	O
with	O
Microsoft	B-Application
SAPI	I-Application
as	O
its	O
speech	O
engine	O
.	O
</s>
<s>
It	O
provided	O
support	O
for	O
Microsoft	B-Application
Windows	I-Application
2000	I-Application
onwards	O
,	O
and	O
provided	O
screen	O
reading	O
capabilities	O
such	O
as	O
basic	O
support	O
for	O
some	O
third-party	O
software	O
and	O
web	O
browsing	O
.	O
</s>
<s>
Towards	O
the	O
end	O
of	O
2006	O
,	O
Curran	O
named	O
his	O
project	O
Nonvisual	B-Language
Desktop	I-Language
Access	I-Language
(	O
NVDA	O
)	O
and	O
released	O
version	O
0.5	O
the	O
following	O
year	O
.	O
</s>
<s>
2009	O
saw	O
support	O
for	O
64-bit	B-Device
versions	O
of	O
Windows	O
as	O
well	O
as	O
greater	O
program	O
stability	O
in	O
2010	O
.	O
</s>
<s>
Major	O
code	O
restructuring	O
to	O
support	O
third-party	O
modules	O
,	O
coupled	O
with	O
basic	O
support	O
for	O
Windows	B-Application
8	I-Application
,	O
became	O
available	O
in	O
2011	O
.	O
</s>
<s>
Throughout	O
2012	O
,	O
NVDA	O
gained	O
improved	O
support	O
for	O
Windows	B-Application
8	I-Application
,	O
ability	O
to	O
perform	O
automatic	O
updates	O
,	O
included	O
add-ons	O
manager	O
to	O
manage	O
third-party	O
add-ons	O
,	O
gained	O
improved	O
support	O
for	O
entering	O
East	O
Asian	O
text	O
and	O
introduced	O
touchscreen	B-Device
support	O
,	O
the	O
first	O
of	O
its	O
kind	O
for	O
third-party	O
screen	O
readers	O
for	O
Windows	O
.	O
</s>
<s>
NVDA	O
gained	O
support	O
for	O
Microsoft	B-Application
PowerPoint	I-Application
in	O
2013	O
and	O
was	O
updated	O
in	O
2014	O
to	O
support	O
PowerPoint	B-Application
2013	O
;	O
NVDA	O
also	O
added	O
enhanced	O
WAI-ARIA	B-General_Concept
support	O
that	O
same	O
year	O
.	O
</s>
<s>
In	O
2015	O
,	O
NVDA	O
gained	O
support	O
for	O
MathML	B-Language
through	O
MathPlayer	O
,	O
along	O
with	O
improved	O
support	O
for	O
Mintty	B-Language
,	O
the	O
desktop	O
client	O
for	O
Skype	B-Application
,	O
and	O
charts	O
in	O
Microsoft	B-Application
Excel	I-Application
,	O
and	O
the	O
ability	O
to	O
lower	O
background	O
audio	O
was	O
introduced	O
in	O
2016	O
.	O
</s>
<s>
Also	O
in	O
2015	O
,	O
NVDA	O
became	O
one	O
of	O
the	O
first	O
screen	O
readers	O
to	O
support	O
Windows	B-Operating_System
10	I-Operating_System
and	O
added	O
support	O
for	O
Microsoft	B-Application
Edge	I-Application
in	O
an	O
experimental	O
capacity	O
.	O
</s>
<s>
NVDA	O
uses	O
eSpeak	B-Language
as	O
its	O
integrated	O
speech	O
synthesizer	O
.	O
</s>
<s>
It	O
also	O
supports	O
the	O
Microsoft	O
Speech	O
platform	O
synthesiser	O
,	O
ETI	O
Eloquence	O
and	O
also	O
supports	O
SAPI	B-Application
synthesizers	O
.	O
</s>
<s>
Besides	O
general	O
Windows	O
functionality	O
,	O
NVDA	O
works	O
with	O
software	O
such	O
as	O
Microsoft	O
office	O
applications	O
,	O
WordPad	B-Application
,	O
Notepad	B-Application
,	O
Windows	B-Device
Media	I-Device
Player	I-Device
,	O
web	O
browsers	O
such	O
as	O
Mozilla	B-Application
Firefox	I-Application
,	O
Google	B-Application
Chrome	I-Application
,	O
Internet	B-Application
Explorer	I-Application
,	O
and	O
Microsoft	B-Application
Edge	I-Application
.	O
</s>
<s>
It	O
supports	O
most	O
email	O
clients	O
such	O
as	O
Outlook	B-Application
,	O
Mozilla	B-Application
Thunderbird	I-Application
,	O
and	O
Outlook	B-Application
Express	I-Application
.	O
</s>
<s>
NVDA	O
also	O
works	O
with	O
most	O
functions	O
of	O
Microsoft	B-Application
Word	I-Application
,	O
Microsoft	B-Application
PowerPoint	I-Application
and	O
Microsoft	B-Application
Excel	I-Application
.	O
</s>
<s>
The	O
free	O
office	O
suites	O
LibreOffice	B-Application
and	O
OpenOffice.org	B-Application
are	O
supported	O
by	O
way	O
of	O
the	O
Java	B-Language
Access	I-Language
Bridge	I-Language
package	O
.	O
</s>
<s>
Since	O
early	O
2009	O
,	O
NVDA	O
supports	O
the	O
WAI-ARIA	B-General_Concept
standard	O
for	O
Accessible	B-General_Concept
Rich	I-General_Concept
Internet	I-General_Concept
Applications	I-General_Concept
,	O
to	O
facilitate	O
better	O
accessibility	O
of	O
web	O
applications	O
for	O
blind	O
users	O
.	O
</s>
<s>
NVDA	O
is	O
organized	O
into	O
various	O
subsystems	O
,	O
including	O
the	O
core	B-General_Concept
loop	I-General_Concept
,	O
add-ons	O
manager	O
,	O
app	O
modules	O
,	O
event	O
handler	O
and	O
input	O
and	O
output	O
handlers	O
,	O
along	O
with	O
modules	O
to	O
support	O
accessibility	O
APIs	B-Application
such	O
as	O
Microsoft	O
Active	O
Accessibility	O
.	O
</s>
<s>
NVDA	O
also	O
features	O
various	O
graphical	O
user	O
interfaces	O
of	O
its	O
own	O
powered	O
by	O
wxPython	B-Language
,	O
such	O
as	O
various	O
preference	O
dialogs	O
,	O
and	O
setup	O
and	O
update	O
management	O
dialogs	O
.	O
</s>
<s>
Various	O
information	O
about	O
an	O
object	O
such	O
as	O
its	O
name	O
,	O
value	O
and	O
screen	O
coordinates	O
are	O
gathered	O
by	O
NVDA	O
through	O
accessibility	O
APIs	B-Application
exposed	O
by	O
an	O
object	O
,	O
such	O
as	O
through	O
UIA	B-Application
(	O
User	O
Interface	O
Automation	O
)	O
.	O
</s>
<s>
It	O
provides	O
dedicated	O
commands	O
to	O
move	O
through	O
object	O
hierarchy	O
within	O
an	O
application	O
,	O
as	O
well	O
as	O
an	O
interactive	O
python	B-Language
console	O
to	O
perform	O
focus	O
manipulation	O
,	O
monitoring	O
objects	O
for	O
events	O
and	O
test	O
code	O
for	O
improving	O
accessibility	O
of	O
an	O
application	O
to	O
be	O
packaged	O
in	O
an	O
app	O
module	O
.	O
</s>
<s>
From	O
2006	O
to	O
2013	O
,	O
NVDA	O
's	O
source	O
code	O
was	O
managed	O
via	O
Bazaar	B-Protocol
,	O
with	O
NV	O
Access	O
switching	O
to	O
Git	B-Application
in	O
2013	O
,	O
citing	O
development	O
progress	O
with	O
Bazaar	B-Protocol
.	O
</s>
