<s>
Polymer	B-Language
is	O
an	O
open-source	B-Application
JavaScript	B-Language
library	I-Language
for	O
building	O
web	B-Application
applications	I-Application
using	O
Web	B-Language
Components	I-Language
.	O
</s>
<s>
The	O
library	O
is	O
being	O
developed	O
by	O
Google	B-Application
developers	O
and	O
contributors	O
on	O
GitHub	B-Application
.	O
</s>
<s>
Modern	O
design	O
principles	O
are	O
implemented	O
as	O
a	O
separate	O
project	O
using	O
Google	B-Application
's	I-Application
Material	B-Application
Design	I-Application
design	O
principles	O
.	O
</s>
<s>
Polymer	B-Language
is	O
used	O
by	O
a	O
number	O
of	O
Google	B-Application
services	O
and	O
websites	O
,	O
including	O
YouTube	B-General_Concept
,	O
YouTube	B-General_Concept
Gaming	I-General_Concept
,	O
the	O
redesigned	O
Google	B-Application
Earth	I-Application
(	O
since	O
2017	O
)	O
,	O
Google	B-Application
I/O	I-Application
2015	O
and	O
2016	O
websites	O
,	O
Google	B-Application
Play	I-Application
Music	I-Application
,	O
redesign	O
of	O
Google	B-Application
Sites	I-Application
and	O
Allo	B-Protocol
for	O
web	O
(	O
until	O
its	O
shutdown	O
in	O
2019	O
)	O
.	O
</s>
<s>
Other	O
notable	O
users	O
include	O
Netflix	O
,	O
Electronics	O
Arts	O
,	O
Comcast	O
,	O
Nuxeo	B-Language
,	O
Coca-Cola	O
,	O
McDonald	O
's	O
,	O
BBVA	O
,	O
IBM	O
and	O
General	O
Electric	O
.	O
</s>
<s>
Public	O
development	O
of	O
Polymer	B-Language
began	O
in	O
November	O
2013	O
with	O
the	O
release	O
of	O
a	O
Promises	O
Polyfill	B-Protocol
.	O
</s>
<s>
This	O
steadily	O
expanded	O
into	O
a	O
web	O
design	O
library	O
covering	O
visual	O
styling	O
guidelines	O
(	O
via	O
Material	B-Application
Design	I-Application
)	O
,	O
data	B-General_Concept
binding	I-General_Concept
,	O
and	O
a	O
large	O
number	O
of	O
"	O
Core	O
"	O
and	O
"	O
Paper	O
"	O
Web	B-Language
Components	I-Language
.	O
</s>
<s>
Core	O
components	O
were	O
originally	O
envisioned	O
to	O
encompass	O
generic	O
functionality	O
that	O
would	O
be	O
essential	O
to	O
most	O
websites	O
,	O
while	O
Paper	O
components	O
were	O
intended	O
to	O
provide	O
more	O
specialized	O
components	O
with	O
Material	B-Application
Design	I-Application
concepts	O
forming	O
a	O
key	O
part	O
of	O
their	O
design	O
.	O
</s>
<s>
Google	B-Application
continued	O
to	O
revise	O
the	O
design	O
of	O
Polymer	B-Language
after	O
the	O
release	O
of	O
0.5	O
,	O
with	O
special	O
consideration	O
given	O
to	O
the	O
performance	O
issues	O
a	O
number	O
of	O
developers	O
found	O
.	O
</s>
<s>
This	O
culminated	O
with	O
the	O
release	O
of	O
Polymer	B-Language
1.0	O
in	O
2015	O
,	O
which	O
was	O
the	O
first	O
"	O
production	O
ready	O
"	O
version	O
of	O
the	O
library	O
.	O
</s>
<s>
Version	O
1.0	O
significantly	O
improved	O
the	O
performance	O
of	O
Polymer	B-Language
,	O
reducing	O
load	O
times	O
by	O
up	O
to	O
7	O
times	O
.	O
</s>
<s>
With	O
version	O
1.0	O
Google	B-Application
split	O
the	O
elements	O
from	O
the	O
Polymer	B-Language
project	O
to	O
clearly	O
distinguish	O
the	O
elements	O
catalog	O
from	O
the	O
Polymer	B-Language
polyfill	B-Protocol
&	O
webcomponents-sugaring	O
library	O
.	O
</s>
<s>
On	O
14	O
–	O
15	O
September	O
2015	O
,	O
Google	B-Application
organized	O
a	O
Polymer	B-Language
Summit	O
in	O
Amsterdam	O
.	O
</s>
<s>
On	O
17	O
–	O
18	O
October	O
2016	O
,	O
Google	B-Application
organized	O
a	O
Polymer	B-Language
Summit	O
in	O
London	O
.	O
</s>
<s>
On	O
22	O
–	O
23	O
August	O
2017	O
,	O
Google	B-Application
organized	O
a	O
Polymer	B-Language
Summit	O
in	O
Copenhagen	O
.	O
</s>
<s>
On	O
2	O
May	O
2018	O
,	O
the	O
Polymer	B-Language
team	O
announced	O
that	O
any	O
future	O
development	O
in	O
Polymer	B-Language
will	O
shift	O
away	O
from	O
its	O
two-way	O
binding	O
and	O
its	O
template	O
system	O
,	O
and	O
will	O
focus	O
on	O
LitElement	B-Language
(	O
still	O
part	O
of	O
Polymer	B-Language
)	O
and	O
one-way	O
bindings	O
.	O
</s>
<s>
Polymer	B-Language
provides	O
a	O
number	O
of	O
features	O
over	O
vanilla	B-General_Concept
Web	B-Language
Components	I-Language
:	O
</s>
<s>
Polymer	B-Language
has	O
begun	O
to	O
gain	O
increasing	O
recognition	O
in	O
the	O
market	O
,	O
with	O
spikes	O
in	O
use	O
in	O
2015	O
and	O
2016	O
as	O
documented	O
by	O
the	O
website	O
BuiltWith	O
.	O
</s>
<s>
Custom	O
elements	O
can	O
be	O
created	O
using	O
ES	B-Language
(	O
ECMAScript	B-Language
,	O
most	O
commonly	O
JavaScript	B-Language
)	O
modules	O
with	O
classes	O
.	O
</s>
<s>
Custom	O
element	O
definition	O
comprises	O
CSS	B-Language
style	I-Language
,	O
HTML	B-Language
template	O
of	O
the	O
element	O
's	O
local	O
DOM	B-General_Concept
,	O
element	O
properties	O
,	O
lifecycle	O
callbacks	O
and	O
JavaScript	B-Language
methods	O
:	O
</s>
<s>
The	O
element	O
defined	O
above	O
can	O
be	O
used	O
in	O
HTML	B-Language
code	I-Language
:	O
</s>
