<s>
An	O
Internet	B-Application
Explorer	I-Application
shell	I-Application
is	O
any	O
computer	O
program	O
(	O
web	B-Application
browser	I-Application
or	O
otherwise	O
)	O
that	O
uses	O
the	O
Internet	B-Application
Explorer	I-Application
browser	B-Protocol
engine	I-Protocol
,	O
known	O
as	O
MSHTML	B-Application
and	O
previously	O
Trident	B-Application
.	O
</s>
<s>
This	O
engine	O
is	O
closed-source	B-Application
,	O
but	O
Microsoft	O
has	O
exposed	O
an	O
application	B-Application
programming	I-Application
interface	I-Application
(	O
API	B-Application
)	O
that	O
permits	O
the	O
developers	O
to	O
instantiate	O
either	O
MSHTML	B-Application
or	O
a	O
full-fledged	O
chromeless	B-Application
Internet	B-Application
Explorer	I-Application
(	O
known	O
as	O
the	O
WebBrowser	B-Application
control	O
)	O
within	O
the	O
graphical	B-Application
user	I-Application
interface	I-Application
of	O
their	O
software	O
.	O
</s>
<s>
These	O
applications	O
supplement	O
some	O
of	O
the	O
usual	O
user	B-Application
interface	I-Application
components	O
of	O
Internet	B-Application
Explorer	I-Application
(	O
IE	O
)	O
for	O
browsing	O
,	O
adding	O
features	O
such	O
as	O
popup	O
blocking	O
and	O
tabbed	O
browsing	O
.	O
</s>
<s>
For	O
example	O
,	O
MSN	B-Protocol
Explorer	I-Protocol
can	O
be	O
considered	O
an	O
Internet	B-Application
Explorer	I-Application
shell	I-Application
,	O
in	O
that	O
it	O
is	O
essentially	O
an	O
expansion	O
of	O
IE	O
with	O
added	O
MSN-related	O
functionality	O
.	O
</s>
<s>
A	O
more	O
complete	O
list	O
of	O
MSHTML-based	O
browsers	B-Application
can	O
be	O
found	O
under	O
the	O
list	O
of	O
web	B-Application
browsers	I-Application
.	O
</s>
<s>
Other	O
applications	O
that	O
are	O
not	O
primarily	O
for	O
web	O
browsing	O
,	O
such	O
as	O
Intuit	O
's	O
Quicken	O
and	O
QuickBooks	O
,	O
AOL	O
,	O
Winamp	B-Application
,	O
and	O
RealPlayer	B-Application
,	O
use	O
the	O
rendering	O
engine	O
to	O
provide	O
a	O
limited-functionality	O
"	O
mini	O
"	O
browser	B-Application
within	O
their	O
own	O
user	B-Application
interfaces	I-Application
.	O
</s>
<s>
On	O
Windows	O
,	O
components	O
of	O
Internet	B-Application
Explorer	I-Application
are	O
also	O
used	O
in	O
Windows	B-Protocol
Explorer	I-Protocol
,	O
the	O
operating	B-Operating_System
system	I-Operating_System
shell	I-Operating_System
that	O
provides	O
the	O
default	O
file	B-Application
system	I-Application
browsing	O
and	O
desktop	O
services	O
.	O
</s>
<s>
For	O
example	O
,	O
folder	O
views	O
in	O
Windows	B-Protocol
Explorer	I-Protocol
on	O
versions	O
of	O
Windows	O
prior	O
to	O
Windows	B-Application
XP	I-Application
utilize	O
IE	O
's	O
DHTML	B-General_Concept
processing	O
abilities	O
;	O
they	O
are	O
essentially	O
little	O
web	O
pages	O
.	O
</s>
<s>
MSHTML	B-Application
was	O
,	O
until	O
Outlook	B-Application
2007	I-Application
,	O
also	O
used	O
to	O
render	O
HTML	B-Language
portions	O
of	O
email	O
messages	O
in	O
Microsoft	B-Application
Outlook	I-Application
and	O
Outlook	B-Application
Express	I-Application
email	B-Protocol
clients	I-Protocol
(	O
Outlook	B-Application
2007	I-Application
now	O
uses	O
Microsoft	B-Application
Word	I-Application
to	O
render	O
HTML	B-Language
e-mail	O
)	O
.	O
</s>
<s>
This	O
integration	O
,	O
while	O
convenient	O
,	O
is	O
an	O
often-exploited	O
"	O
back	O
door	O
"	O
,	O
since	O
the	O
Internet	B-Application
Explorer	I-Application
components	O
make	O
available	O
more	O
of	O
the	O
functionality	O
within	O
the	O
HTML	B-Language
code	I-Language
than	O
some	O
feel	O
should	O
be	O
permitted	O
in	O
the	O
context	O
of	O
email	O
messages	O
,	O
and	O
Outlook	O
and	O
Outlook	B-Application
Express	I-Application
have	O
,	O
historically	O
,	O
not	O
done	O
enough	O
to	O
prevent	O
malicious	O
code	O
from	O
taking	O
advantage	O
of	O
that	O
functionality	O
.	O
</s>
<s>
The	O
latest	O
updates	O
for	O
Outlook	B-Application
Express	I-Application
,	O
which	O
require	O
Windows	B-Application
XP	I-Application
and	O
are	O
distributed	O
with	O
Service	O
Pack	O
2	O
,	O
are	O
intended	O
to	O
improve	O
this	O
situation	O
.	O
</s>
<s>
Outlook	B-Application
2003	I-Application
already	O
includes	O
many	O
of	O
the	O
updates	O
.	O
</s>
<s>
Microsoft	O
Windows	O
also	O
supports	O
HTML	B-Application
Applications	I-Application
,	O
computer	O
programs	O
written	O
in	O
HTML	B-Language
,	O
CSS	O
and	O
JavaScript	O
and	O
bear	O
a	O
.hta	B-Application
filename	O
extension	O
.	O
</s>
<s>
They	O
run	O
with	O
HTML	B-Application
Application	I-Application
Host	O
,	O
which	O
is	O
a	O
plain	O
Internet	B-Application
Explorer	I-Application
shell	I-Application
without	O
any	O
GUI	B-Application
elements	O
around	O
it	O
.	O
</s>
