<s>
The	O
C4	B-Application
model	I-Application
is	O
a	O
lean	O
graphical	O
notation	O
technique	O
for	O
modelling	O
the	O
architecture	O
of	O
software	O
systems	O
.	O
</s>
<s>
It	O
is	O
based	O
on	O
a	O
structural	O
decomposition	O
of	O
a	O
system	O
into	O
containers	O
and	O
components	B-Architecture
and	O
relies	O
on	O
existing	O
modelling	O
techniques	O
such	O
as	O
the	O
Unified	B-Language
Modelling	I-Language
Language	I-Language
(	O
UML	B-Language
)	O
or	O
Entity	O
Relation	O
Diagrams	O
(	O
ERD	O
)	O
for	O
the	O
more	O
detailed	O
decomposition	O
of	O
the	O
architectural	O
building	O
blocks	O
.	O
</s>
<s>
The	O
C4	B-Application
model	I-Application
was	O
created	O
by	O
the	O
software	B-Architecture
architect	I-Architecture
Simon	O
Brown	O
between	O
2006	O
and	O
2011	O
on	O
the	O
roots	O
of	O
Unified	B-Language
Modelling	I-Language
Language	I-Language
(	O
UML	B-Language
)	O
and	O
the	O
4+1	B-Architecture
architectural	I-Architecture
view	I-Architecture
model	I-Architecture
.	O
</s>
<s>
The	O
C4	B-Application
model	I-Application
documents	O
the	O
architecture	O
of	O
a	O
software	O
system	O
,	O
by	O
showing	O
multiple	O
points	O
of	O
view	O
that	O
explain	O
the	O
decomposition	O
of	O
a	O
system	O
into	O
containers	O
and	O
components	B-Architecture
,	O
the	O
relationship	O
between	O
these	O
elements	O
,	O
and	O
,	O
where	O
appropriate	O
,	O
the	O
relation	O
with	O
its	O
users	O
.	O
</s>
<s>
Component	O
diagrams	O
(	O
level	O
3	O
)	O
:	O
decompose	O
containers	O
into	O
interrelated	O
components	B-Architecture
,	O
and	O
relate	O
the	O
components	B-Architecture
to	O
other	O
containers	O
or	O
other	O
systems	O
;	O
</s>
<s>
The	O
C4	B-Application
model	I-Application
relies	O
at	O
this	O
level	O
on	O
existing	O
notations	O
such	O
as	O
Unified	B-Language
Modelling	I-Language
Language	I-Language
(	O
UML	B-Language
)	O
,	O
Entity	O
Relation	O
Diagrams	O
(	O
ERD	O
)	O
or	O
diagrams	O
generated	O
by	O
Integrated	B-Application
Development	I-Application
Environments	I-Application
(	O
IDE	O
)	O
.	O
</s>
<s>
For	O
level	O
1	O
to	O
3	O
,	O
the	O
C4	B-Application
model	I-Application
uses	O
5	O
basic	O
diagramming	O
elements	O
:	O
persons	O
,	O
software	O
systems	O
,	O
containers	O
,	O
components	B-Architecture
and	O
relationships	O
.	O
</s>
<s>
Instead	O
,	O
the	O
C4	B-Application
model	I-Application
recommends	O
using	O
simple	O
diagrams	O
based	O
on	O
nested	O
boxes	O
in	O
order	O
to	O
facilitate	O
interactive	O
collaborative	O
drawing	O
.	O
</s>
<s>
The	O
C4	B-Application
model	I-Application
facilitates	O
collaborative	O
visual	O
architecting	O
and	O
evolutionary	O
architecture	O
in	O
the	O
context	O
of	O
agile	O
teams	O
where	O
more	O
formal	O
documentation	O
methods	O
and	O
up-front	O
architectural	O
design	O
are	O
not	O
desired	O
.	O
</s>
