<s>
Presto	B-Application
was	O
the	O
browser	B-Protocol
engine	I-Protocol
of	O
the	O
Opera	B-Application
web	I-Application
browser	I-Application
from	O
the	O
release	O
of	O
Opera	B-Application
7	O
on	O
28	O
January	O
2003	O
,	O
until	O
the	O
release	O
of	O
Opera	B-Application
15	O
on	O
2	O
July	O
2013	O
,	O
at	O
which	O
time	O
Opera	B-Application
switched	O
to	O
using	O
the	O
Blink	B-Language
engine	O
that	O
was	O
originally	O
created	O
for	O
Chromium	B-Language
.	O
</s>
<s>
Presto	B-Application
was	O
also	O
used	O
to	O
power	O
the	O
Opera	B-Protocol
Mini	I-Protocol
and	O
Opera	B-Language
Mobile	I-Language
browsers	O
.	O
</s>
<s>
Presto	B-Application
is	O
a	O
dynamic	O
engine	O
.	O
</s>
<s>
Web	O
pages	O
can	O
be	O
re-rendered	O
completely	O
or	O
partially	O
in	O
response	O
to	O
DOM	B-Application
events	I-Application
.	O
</s>
<s>
Its	O
releases	O
saw	O
a	O
number	O
of	O
bug	O
fixes	O
and	O
optimizations	O
to	O
improve	O
the	O
speed	O
of	O
the	O
ECMAScript	B-Language
(	O
JavaScript	B-Language
)	O
engine	O
.	O
</s>
<s>
It	O
is	O
proprietary	B-Application
and	O
only	O
available	O
as	O
a	O
part	O
of	O
the	O
Opera	B-Application
browsers	I-Application
.	O
</s>
<s>
A	O
succession	O
of	O
ECMAScript	B-Language
engines	I-Language
have	O
been	O
used	O
with	O
Opera	B-Application
.	O
</s>
<s>
Pre-Presto	O
versions	O
of	O
Opera	B-Application
used	O
the	O
Linear	O
A	O
engine	O
.	O
</s>
<s>
Opera	B-Application
versions	O
based	O
on	O
the	O
Core	O
fork	B-Application
of	O
Presto	B-Application
,	O
Opera	B-Application
7.0	O
through	O
9.27	O
,	O
used	O
the	O
Linear	O
B	O
engine	O
.	O
</s>
<s>
The	O
Futhark	O
engine	O
is	O
used	O
in	O
some	O
versions	O
on	O
the	O
Core	O
2	O
fork	B-Application
of	O
Presto	B-Application
,	O
namely	O
Opera	B-Application
9.5	O
to	O
Opera	B-Application
10.10	O
.	O
</s>
<s>
When	O
released	O
it	O
was	O
the	O
fastest	O
engine	O
around	O
,	O
but	O
in	O
2008	O
a	O
new	O
generation	O
of	O
ECMAScript	B-Language
engines	I-Language
from	O
Google	B-Application
(	O
V8	B-Language
)	O
,	O
Mozilla	B-Operating_System
(	O
SpiderMonkey	B-Language
)	O
,	O
and	O
Apple	O
(	O
JavaScriptCore	O
)	O
took	O
one	O
more	O
step	O
,	O
introducing	O
native	O
code	O
generation	O
.	O
</s>
<s>
In	O
early	O
2009	O
,	O
Opera	B-Application
introduced	O
the	O
Carakan	O
engine	O
.	O
</s>
<s>
Early	O
access	O
in	O
the	O
Opera	B-Application
10.50	O
pre-alpha	O
showed	O
that	O
it	O
is	O
as	O
fast	O
as	O
the	O
fastest	O
competitors	O
,	O
being	O
the	O
winner	O
in	O
2	O
out	O
of	O
the	O
3	O
most	O
used	O
benchmarks	O
.	O
</s>
<s>
Presto	B-Application
VersionECMAScript	O
engineBrowser	O
code	O
nameOpera	O
BrowserOpera	O
MobileOther	O
useNew	O
featurespre	O
Prestononeunnamed3.5pre	O
PrestoLinear	O
AElektra/unnamed	O
Elektra	B-Application
was	O
originally	O
the	O
codename	O
of	O
Opera	B-Application
4.0	O
,	O
but	O
later	O
came	O
to	O
refer	O
more	O
generally	O
to	O
the	O
layout	B-Protocol
engine	I-Protocol
used	O
in	O
versions	O
3.5	O
through	O
6.4.0	O
1.0	O
Linear	O
Bunnamed7.0a	O
completely	O
new	O
rendering	O
engine	O
,	O
Favicon	O
support8.5	O
"	O
Bolton	O
"	O
version	O
:	O
1st	O
completely	O
free	O
download	O
version	O
(	O
ad-free	O
toolbar	O
)	O
2.0Merlin9.0Internet	O
ChannelCanvas	O
,	O
Acid2	O
Test	O
:	O
passed	O
,	O
Rich	O
text	O
editing	O
,	O
XSLT	O
,	O
and	O
XPath2.1	O
Futhark	O
Kestrel9.59.5Nintendo	O
DSi	O
BrowserSVG	O
Tiny	O
1.2	O
,	O
SVG	B-Application
as	O
CSS	O
,	O
SVG	B-Application
as	O
,	O
Audio	O
object2.1.19.6Scope	O
API	O
,	O
SVG	B-Application
as	O
Favicon2.2	O
Peregrine9.72.2.1510.010.19.8Acid3	O
test	O
:	O
100/100	O
,	O
pixel-perfect	O
,	O
Web	O
fonts	O
,	O
CSS	O
Selectors	O
API	O
,	O
RGBA	O
&	O
HSLA	O
opacity	O
,	O
TLS	B-Protocol
1.2.	O
,	O
FPS	O
in	O
SVG	B-Application
,	O
SVG	B-Application
fonts	O
in	O
HTML2.3Opera	O
Devices	O
SDK	O
10CSS3	O
:	O
border-image	O
,	O
border-radius	O
(	O
rounded	O
corners	O
)	O
,	O
box-shadow	O
,	O
transitions	O
;	O
HTML5	B-Application
:	O
<audio> and <video> elements2.410CSS2.1: visibility:collapse; CSS3 : transforms; HTML5: <canvas> shadows, Web Database, Web Storage, window.btoa, and window.atob2.5.24 Carakan Evenes10.510.1Opera Mini serverCSS3: multiple backgrounds; HTML5: <canvas> Text2.6.3010.6WebM; HTML5: AppCache, Geolocation, Web Workers2.7.62 Kjevik11.011.0Extensions, WebSocket 2.8.131 Barracuda 11.1 11.1 Opera Mini server 4.27WebP, File API, CSS3 gradients (only for the background and background-image properties ) : -o-linear-gradient( ) , -o-repeating-linear-gradient( ) ; Support for <color-stop>	O
added	O
.	O
</s>
<s>
The	O
source	O
code	O
for	O
version	O
12.15	O
was	O
leaked	O
to	O
GitHub	B-Application
on	O
February	O
11	O
,	O
2016	O
.	O
</s>
<s>
Opera	B-Application
Software	O
has	O
confirmed	O
the	O
authenticity	O
of	O
the	O
source	O
code	O
.	O
</s>
<s>
The	O
ECMAScript	B-Language
engines	I-Language
used	O
with	O
Opera	B-Application
have	O
been	O
named	O
after	O
ancient	O
and	O
traditional	O
writing	O
scripts	O
,	O
including	O
ancient	O
Greek	O
Linear	O
A	O
and	O
Linear	O
B	O
,	O
Runic	O
Futhark	O
,	O
and	O
Javanese	O
Carakan	O
.	O
</s>
