<s>
A	O
software	B-Application
development	I-Application
kit	I-Application
(	O
SDK	O
)	O
is	O
a	O
collection	O
of	O
software	B-Application
development	I-Application
tools	I-Application
in	O
one	O
installable	O
package	O
.	O
</s>
<s>
They	O
facilitate	O
the	O
creation	O
of	O
applications	B-Application
by	O
having	O
a	O
compiler	O
,	O
debugger	O
and	O
sometimes	O
a	O
software	B-Architecture
framework	I-Architecture
.	O
</s>
<s>
They	O
are	O
normally	O
specific	O
to	O
a	O
hardware	O
platform	O
and	O
operating	B-General_Concept
system	I-General_Concept
combination	O
.	O
</s>
<s>
To	O
create	O
applications	B-Application
with	O
advanced	O
functionalities	O
such	O
as	O
advertisements	O
,	O
push	O
notifications	O
,	O
etc	O
;	O
most	O
application	B-Application
software	I-Application
developers	B-Application
use	O
specific	O
software	B-Application
development	I-Application
kits	I-Application
.	O
</s>
<s>
For	O
example	O
,	O
the	O
development	O
of	O
an	O
Android	B-Application
app	O
on	O
the	O
Java	B-Language
platform	O
requires	O
a	O
Java	B-Language
Development	I-Language
Kit	I-Language
.	O
</s>
<s>
For	O
iOS	B-Application
applications	I-Application
(	O
apps	O
)	O
the	O
iOS	B-Operating_System
SDK	I-Operating_System
is	O
required	O
.	O
</s>
<s>
For	O
Universal	B-Device
Windows	I-Device
Platform	I-Device
the	O
.NET	B-Application
Framework	I-Application
SDK	I-Application
might	O
be	O
used	O
.	O
</s>
<s>
Some	O
prominent	O
creators	O
of	O
these	O
types	O
of	O
SDKs	O
include	O
Google	B-Application
,	O
Smaato	O
,	O
InMobi	O
,	O
and	O
Facebook	B-Application
.	I-Application
</s>
<s>
An	O
SDK	O
can	O
take	O
the	O
form	O
of	O
application	B-Application
programming	I-Application
interfaces	I-Application
(	O
APIs	B-Application
)	O
in	O
the	O
form	O
of	O
on-device	O
libraries	B-Library
of	O
reusable	O
functions	O
used	O
to	O
interface	O
to	O
a	O
particular	O
programming	O
language	O
,	O
or	O
it	O
may	O
be	O
as	O
complex	O
as	O
hardware-specific	O
tools	B-Application
that	O
can	O
communicate	O
with	O
a	O
particular	O
embedded	B-Architecture
system	I-Architecture
.	O
</s>
<s>
Common	O
tools	B-Application
include	O
debugging	O
facilities	O
and	O
other	O
utilities	B-Application
,	O
often	O
presented	O
in	O
an	O
integrated	B-Application
development	I-Application
environment	I-Application
(	O
IDE	O
)	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
proprietary	O
SDK	O
is	O
generally	O
incompatible	O
with	O
free	B-Application
software	I-Application
development	I-Application
,	O
while	O
a	O
GPL-licensed	O
SDK	O
could	O
be	O
incompatible	O
with	O
proprietary	O
software	O
development	O
,	O
for	O
legal	O
reasons	O
.	O
</s>
<s>
However	O
,	O
SDKs	O
built	O
under	O
the	O
GNU	B-Application
Lesser	I-Application
General	I-Application
Public	I-Application
License	I-Application
(	O
LGPL	B-Application
)	O
are	O
typically	O
usable	O
for	O
proprietary	O
development	O
.	O
</s>
<s>
For	O
example	O
,	O
AirTag	B-Operating_System
's	O
2021	O
NFC	O
SDK	O
included	O
both	O
the	O
paying	O
and	O
the	O
reading	O
halves	O
of	O
the	O
necessary	O
hardware	O
stack	O
.	O
</s>
<s>
The	O
average	O
Android	B-Application
mobile	I-Application
app	O
implements	O
15.6	O
separate	O
SDKs	O
,	O
with	O
gaming	O
apps	O
implementing	O
on	O
average	O
17.5	O
different	O
SDKs	O
.	O
</s>
<s>
The	O
most	O
popular	O
SDK	O
categories	O
for	O
Android	B-Application
mobile	I-Application
apps	O
are	O
analytics	O
and	O
advertising	O
.	O
</s>
<s>
Malicious	O
SDKs	O
(	O
with	O
honest	O
intentions	O
or	O
not	O
)	O
can	O
violate	O
users	O
 '	O
data	O
privacy	O
,	O
damage	O
app	O
performance	O
,	O
or	O
even	O
cause	O
apps	O
to	O
be	O
banned	O
from	O
Google	B-Application
Play	I-Application
or	O
the	O
App	B-Application
Store	I-Application
.	O
</s>
<s>
New	O
technologies	O
allow	O
app	B-Application
developers	I-Application
to	O
control	O
and	O
monitor	O
client	O
SDKs	O
in	O
real	O
time	O
.	O
</s>
<s>
For	O
instance	O
,	O
both	O
Microsoft	O
and	O
Citrix	B-Application
provide	O
a	O
driver	B-Application
development	I-Application
kit	I-Application
(	O
DDK	O
)	O
for	O
developing	O
device	B-Application
drivers	I-Application
.	O
</s>
<s>
Examples	O
of	O
software	B-Application
development	I-Application
kits	I-Application
for	O
various	O
platforms	O
include	O
:	O
</s>
