<s>
A	O
Notification	B-Application
LED	I-Application
is	O
a	O
small	O
RGB	O
or	O
monochrome	O
LED	O
light	O
usually	O
present	O
on	O
the	O
front-facing	O
screen	O
bezel	O
(	O
display	O
side	O
)	O
of	O
smartphones	B-Application
and	O
feature	B-Device
phones	I-Device
whose	O
purpose	O
is	O
to	O
blink	O
or	O
pulse	O
to	O
notify	O
the	O
phone	O
user	O
of	O
missed	O
calls	O
,	O
incoming	O
SMS	B-Device
messages	O
,	O
notifications	O
from	O
other	O
apps	O
,	O
low	O
battery	O
warning	O
,	O
etc.	O
,	O
and	O
optionally	O
to	O
facilitate	O
locating	O
the	O
mobile	O
phone	O
in	O
darkness	O
.	O
</s>
<s>
It	O
is	O
a	O
part	O
of	O
the	O
device	O
's	O
notification	B-Application
system	I-Application
that	O
uses	O
a	O
cloud-powered	O
push	B-General_Concept
notification	I-General_Concept
service	I-General_Concept
to	O
relay	O
remote	O
notification	O
messages	O
to	O
the	O
user	O
,	O
or	O
local	O
notifications	O
.	O
</s>
<s>
Similar	O
to	O
audio	O
notifications	O
,	O
a	O
notification	B-Application
LED	I-Application
is	O
a	O
very	O
battery-efficient	O
way	O
to	O
inform	O
the	O
user	O
of	O
new	O
notifications	O
without	O
turning	O
on	O
the	O
screen	O
at	O
all	O
.	O
</s>
<s>
In	O
any	O
mobile	O
phone	O
or	O
smartphone	B-Application
,	O
battery	O
life	O
is	O
an	O
important	O
consideration	O
and	O
the	O
display	O
is	O
the	O
component	O
that	O
consumes	O
the	O
maximum	O
battery	O
when	O
it	O
is	O
fully	O
lit	O
up	O
.	O
</s>
<s>
By	O
blinking	O
unobtrusively	O
,	O
the	O
notification	B-Application
LED	I-Application
light	O
discreetly	O
conveys	O
to	O
the	O
user	O
of	O
any	O
potentially	O
important	O
message	O
or	O
call	O
.	O
</s>
<s>
In	O
some	O
phones	O
,	O
the	O
LED	O
notification	B-Application
light	I-Application
is	O
also	O
sometimes	O
designed	O
to	O
glow	O
red	O
when	O
the	O
battery	O
is	O
low	O
,	O
when	O
the	O
battery	O
is	O
charging	O
and	O
turn	O
green	O
when	O
the	O
battery	O
is	O
fully	O
charged	O
.	O
</s>
<s>
While	O
most	O
phones	O
include	O
the	O
notification	B-Application
LED	I-Application
light	O
on	O
the	O
front	O
side	O
,	O
some	O
smartphone	B-Application
manufacturers	O
like	O
LG	O
or	O
Nokia	O
have	O
also	O
integrated	O
it	O
into	O
the	O
power	O
button	O
,	O
while	O
some	O
phones	O
from	O
Motorola	O
,	O
Xiaomi	O
,	O
Razer	O
or	O
ASUS	O
have	O
their	O
brand	O
logo	O
on	O
the	O
back	O
side	O
of	O
the	O
phone	O
,	O
serving	O
as	O
the	O
notification	B-Application
light	I-Application
.	O
</s>
<s>
In	O
some	O
Android	B-Application
and	O
BlackBerry	B-Operating_System
smartphones	B-Application
,	O
the	O
notification	B-Application
LED	I-Application
light	O
's	O
behavior	O
could	O
be	O
customized	O
per	O
app	O
,	O
so	O
that	O
,	O
each	O
color	O
would	O
indicate	O
a	O
different	O
app	O
.	O
</s>
<s>
Apps	O
like	O
WhatsApp	B-Application
or	O
Telegram	B-Application
also	O
include	O
a	O
setting	O
to	O
set	O
this	O
color	O
for	O
the	O
LED	O
light	O
.	O
</s>
<s>
The	O
notification	B-Application
LED	I-Application
light	O
was	O
popular	O
when	O
feature	B-Device
phones	I-Device
were	O
widely	O
used	O
.	O
</s>
<s>
In	O
early	O
smartphones	B-Application
running	O
Windows	O
Mobile	O
or	O
the	O
Android	B-Application
operating	I-Application
system	I-Application
,	O
the	O
LED	O
notification	B-Application
light	I-Application
was	O
also	O
a	O
fairly	O
common	O
feature	O
.	O
</s>
<s>
These	O
smartphones	B-Application
usually	O
had	O
LCD	O
displays	O
,	O
so	O
without	O
the	O
LED	O
present	O
,	O
the	O
entire	O
backlight	O
behind	O
the	O
display	O
would	O
need	O
to	O
be	O
turned	O
on	O
to	O
check	O
for	O
any	O
new	O
notifications	O
.	O
</s>
<s>
Gradually	O
,	O
the	O
smartphone	B-Application
industry	O
has	O
been	O
moving	O
towards	O
OLED	B-Device
displays	I-Device
.	O
</s>
<s>
With	O
this	O
transition	O
,	O
the	O
dedicated	O
notification	B-Application
LED	I-Application
light	O
has	O
slowly	O
been	O
eliminated	O
from	O
newer	O
smartphones	B-Application
.	O
</s>
<s>
There	O
is	O
also	O
a	O
focus	O
by	O
smartphone	B-Application
designers	O
to	O
minimize	O
the	O
screen	O
bezels	O
or	O
keep	O
them	O
very	O
thin	O
,	O
thus	O
leaving	O
no	O
room	O
for	O
the	O
notification	B-Application
LED	I-Application
light	O
.	O
</s>
<s>
As	O
a	O
replacement	O
for	O
the	O
LED	O
light	O
,	O
some	O
smartphones	B-Application
from	O
Samsung	O
,	O
LG	O
,	O
Nokia	O
include	O
an	O
Always	B-Application
On	I-Application
Display	I-Application
feature	O
.	O
</s>
<s>
On	O
OLED	B-Device
displays	I-Device
,	O
the	O
Always-On	O
Display	O
(	O
AOD	O
)	O
shows	O
limited	O
information	O
while	O
the	O
phone	O
is	O
asleep	O
,	O
that	O
is	O
,	O
when	O
the	O
entire	O
display	O
is	O
not	O
lit	O
up	O
.	O
</s>
<s>
With	O
OLED	B-Device
screens	I-Device
,	O
only	O
a	O
part	O
of	O
the	O
screen	O
,	O
or	O
a	O
few	O
pixels	O
on	O
it	O
can	O
be	O
turned	O
on	O
to	O
convey	O
information	O
.	O
</s>
<s>
With	O
any	O
pixel	O
on	O
an	O
OLED	B-Device
screen	I-Device
effectively	O
being	O
a	O
notification	B-Application
LED	I-Application
,	O
software	O
can	O
be	O
used	O
to	O
customize	O
its	O
appearance	O
.	O
</s>
