<s>
In	O
computer	B-General_Concept
programming	I-General_Concept
,	O
a	O
shim	O
is	O
a	O
library	B-Library
that	O
transparently	O
intercepts	O
API	B-Application
calls	O
and	O
changes	O
the	O
arguments	O
passed	O
,	O
handles	O
the	O
operation	O
itself	O
or	O
redirects	O
the	O
operation	O
elsewhere	O
.	O
</s>
<s>
Shims	O
can	O
be	O
used	O
to	O
support	O
an	O
old	O
API	B-Application
in	O
a	O
newer	O
environment	O
,	O
or	O
a	O
new	O
API	B-Application
in	O
an	O
older	O
environment	O
.	O
</s>
<s>
Shims	O
for	O
older	O
APIs	B-Application
typically	O
come	O
about	O
when	O
the	O
behavior	O
of	O
an	O
API	B-Application
changes	O
,	O
thereby	O
causing	O
compatibility	O
issues	O
for	O
older	O
applications	O
which	O
still	O
rely	O
on	O
the	O
older	O
functionality	O
;	O
in	O
such	O
cases	O
,	O
the	O
older	O
API	B-Application
can	O
still	O
be	O
supported	O
by	O
a	O
thin	O
compatibility	B-General_Concept
layer	I-General_Concept
on	O
top	O
of	O
the	O
newer	O
code	O
.	O
</s>
<s>
Shims	O
for	O
newer	O
APIs	B-Application
are	O
defined	O
as	O
:	O
"	O
a	O
library	B-Library
that	O
brings	O
a	O
new	O
API	B-Application
to	O
an	O
older	O
environment	O
,	O
using	O
only	O
the	O
means	O
of	O
that	O
environment.	O
"	O
</s>
<s>
Web	O
polyfills	B-Protocol
implement	O
newer	O
web	O
standards	O
using	O
older	O
standards	O
and	O
JavaScript	B-Language
,	O
if	O
the	O
newer	O
standard	O
is	O
not	O
available	O
in	O
a	O
given	O
web	B-Application
browser	I-Application
.	O
</s>
<s>
Support	O
of	O
AppleTalk	B-Application
on	O
Macintosh	B-Device
computers	I-Device
,	O
during	O
the	O
brief	O
period	O
in	O
which	O
Apple	O
Computer	O
supported	O
the	O
Open	B-Protocol
Transport	I-Protocol
networking	O
system	O
.	O
</s>
<s>
Thousands	O
of	O
Mac	B-Device
programs	O
were	O
based	O
on	O
the	O
AppleTalk	B-Application
protocol	O
;	O
to	O
support	O
these	O
programs	O
,	O
AppleTalk	B-Application
was	O
re-implemented	O
as	O
an	O
OpenTransport	B-Protocol
"	O
stack	O
"	O
,	O
and	O
then	O
re-implemented	O
as	O
an	O
API	B-Application
shim	O
on	O
top	O
of	O
this	O
new	O
library	B-Library
.	O
</s>
<s>
The	O
Microsoft	B-Application
Windows	I-Application
Application	O
Compatibility	O
Toolkit	O
(	O
ACT	O
)	O
uses	O
the	O
term	O
to	O
mean	O
backward	B-General_Concept
compatible	I-General_Concept
libraries	O
.	O
</s>
<s>
Shims	O
simulate	O
the	O
behavior	O
of	O
older	O
versions	O
of	O
Windows	O
for	O
legacy	O
applications	O
that	O
rely	O
on	O
incorrect	O
or	O
deprecated	O
functionality	O
,	O
or	O
correct	O
the	O
way	O
in	O
which	O
poorly	O
written	O
applications	O
call	O
unchanged	O
APIs	B-Application
,	O
for	O
example	O
to	O
fix	O
least-privileged	O
user	O
account	O
(	O
LUA	O
)	O
bugs	B-Error_Name
.	O
</s>
<s>
bind.so	O
is	O
a	O
shim	O
library	B-Library
for	O
Linux	B-Application
that	O
allows	O
any	O
application	O
,	O
regardless	O
of	O
permissions	O
,	O
to	O
bind	O
to	O
a	O
listening	O
socket	O
or	O
specify	O
outgoing	O
IP	O
address	O
.	O
</s>
<s>
In	O
the	O
type	B-Architecture
tunnel	I-Architecture
pattern	I-Architecture
,	O
a	O
generic	O
interface	O
layer	O
uses	O
a	O
family	O
of	O
shims	O
to	O
translate	O
a	O
heterogeneous	O
set	O
of	O
types	O
to	O
a	O
single	O
primitive	O
type	O
used	O
by	O
an	O
underlying	O
API	B-Application
.	O
</s>
