<s>
In	O
electronic	O
design	O
,	O
wire	O
routing	O
,	O
commonly	O
called	O
simply	O
routing	O
,	O
is	O
a	O
step	O
in	O
the	O
design	O
of	O
printed	O
circuit	O
boards	O
(	O
PCBs	B-Language
)	O
and	O
integrated	O
circuits	O
(	O
ICs	O
)	O
.	O
</s>
<s>
It	O
builds	O
on	O
a	O
preceding	O
step	O
,	O
called	O
placement	O
,	O
which	O
determines	O
the	O
location	O
of	O
each	O
active	O
element	O
of	O
an	O
IC	O
or	O
component	O
on	O
a	O
PCB	B-Language
.	O
</s>
<s>
Variants	O
of	O
channel	B-Algorithm
routing	I-Algorithm
have	O
also	O
been	O
shown	O
to	O
be	O
NP-complete	O
,	O
as	O
well	O
as	O
routing	O
which	O
reduces	O
crosstalk	O
,	O
number	O
of	O
vias	O
,	O
and	O
so	O
on	O
.	O
</s>
<s>
Instead	O
,	O
almost	O
all	O
routing	O
is	O
based	O
on	O
heuristics	B-Algorithm
which	O
try	O
to	O
find	O
a	O
solution	O
that	O
is	O
good	O
enough	O
.	O
</s>
<s>
This	O
introduces	O
many	O
additional	O
complications	O
not	O
faced	O
by	O
routers	O
for	O
other	O
applications	O
such	O
as	O
printed	O
circuit	O
board	O
or	O
multi-chip	B-Algorithm
module	I-Algorithm
design	O
.	O
</s>
<s>
Modern	O
PCB	B-Language
design	O
software	O
typically	O
provides	O
"	O
interactive	O
routers	O
"	O
—	O
the	O
drafter	O
selects	O
a	O
pad	O
and	O
clicks	O
a	O
few	O
places	O
to	O
give	O
the	O
EDA	O
tool	O
an	O
idea	O
of	O
where	O
to	O
go	O
,	O
and	O
the	O
EDA	O
tool	O
tries	O
to	O
place	O
wires	O
as	O
close	O
to	O
that	O
path	O
as	O
possible	O
without	O
violating	O
design	O
rule	O
checking	O
(	O
DRC	O
)	O
.	O
</s>
<s>
Modern	O
PCB	B-Language
design	O
software	O
also	O
typically	O
provides	O
"	O
autorouters	O
"	O
that	O
route	O
all	O
remaining	O
unrouted	O
connections	O
without	O
human	O
intervention	O
.	O
</s>
