<s>
RT-Thread	B-Operating_System
is	O
an	O
open-source	B-License
real-time	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
(	O
RTOS	B-Operating_System
)	O
for	O
embedded	B-Architecture
systems	I-Architecture
and	O
Internet	B-Operating_System
of	I-Operating_System
things	I-Operating_System
(	O
IoT	B-Operating_System
)	O
.	O
</s>
<s>
It	O
is	O
developed	O
by	O
the	O
RT-Thread	B-Operating_System
Development	O
Team	O
based	O
in	O
China	O
.	O
</s>
<s>
RT-Thread	B-Operating_System
is	O
aimed	O
to	O
change	O
the	O
current	O
situation	O
in	O
China	O
that	O
there	O
is	O
no	O
well	O
used	O
open-source	B-License
real-time	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
in	O
the	O
microcontroller	B-Architecture
field	O
.	O
</s>
<s>
,	O
RT-Thread	B-Operating_System
was	O
reported	O
to	O
be	O
#3	O
on	O
the	O
list	O
of	O
RTOSes	O
with	O
the	O
largest	O
number	O
of	O
contributors	O
(	O
behind	O
Zephyr	B-Application
and	O
Mbed	B-Operating_System
)	O
.	O
</s>
<s>
In	O
2006	O
,	O
RT-Thread	B-Operating_System
began	O
as	O
an	O
open-source	B-License
real-time	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
(	O
RTOS	B-Operating_System
)	O
that	O
is	O
mainly	O
written	O
in	O
the	O
programming	B-Language
language	I-Language
C	I-Language
.	O
In	O
2017	O
,	O
a	O
second	O
variant	O
was	O
released	O
for	O
resource-constrained	O
microcontrollers	B-Architecture
;	O
it	O
needs	O
a	O
minimum	O
of	O
3	O
kB	O
flash	B-Device
memory	I-Device
or	O
read-only	B-Device
memory	I-Device
(	O
ROM	B-Device
)	O
and	O
1.2	O
kB	O
random-access	B-Architecture
memory	I-Architecture
(	O
RAM	B-Architecture
)	O
.	O
</s>
<s>
Also	O
,	O
RT-Thread	B-Operating_System
'	O
s	O
first	O
variant	O
was	O
named	O
Standard	O
,	O
and	O
second	O
variant	O
was	O
named	O
Nano	O
.	O
</s>
