<s>
The	O
Internationalized	B-Protocol
Resource	I-Protocol
Identifier	I-Protocol
(	O
IRI	O
)	O
is	O
an	O
internet	O
protocol	O
standard	O
which	O
builds	O
on	O
the	O
Uniform	B-Protocol
Resource	I-Protocol
Identifier	I-Protocol
(	O
URI	B-Protocol
)	O
protocol	O
by	O
greatly	O
expanding	O
the	O
set	O
of	O
permitted	O
characters	O
.	O
</s>
<s>
While	O
URIs	B-Protocol
are	O
limited	O
to	O
a	O
subset	O
of	O
the	O
US-ASCII	B-Protocol
character	B-General_Concept
set	I-General_Concept
(	O
characters	O
outside	O
that	O
set	O
must	O
be	O
mapped	O
to	O
octets	O
according	O
to	O
some	O
unspecified	O
character	B-General_Concept
encoding	I-General_Concept
,	O
then	O
percent-encoded	O
)	O
,	O
IRIs	O
may	O
additionally	O
contain	O
most	O
characters	O
from	O
the	O
Universal	O
Character	B-General_Concept
Set	I-General_Concept
(	O
Unicode/ISO	O
10646	O
)	O
,	O
including	O
Chinese	O
,	O
Japanese	O
,	O
Korean	O
,	O
and	O
Cyrillic	O
characters	O
.	O
</s>
<s>
IRIs	O
extend	O
URIs	B-Protocol
by	O
using	O
the	O
Universal	O
Character	B-General_Concept
Set	I-General_Concept
,	O
where	O
URIs	B-Protocol
were	O
limited	O
to	O
ASCII	B-Protocol
,	O
with	O
far	O
fewer	O
characters	O
.	O
</s>
<s>
IRIs	O
are	O
mapped	O
to	O
URIs	B-Protocol
to	O
retain	O
backwards-compatibility	O
with	O
systems	O
that	O
do	O
not	O
support	O
the	O
new	O
format	O
.	O
</s>
<s>
All	O
non-ASCII	O
code	O
points	O
in	O
the	O
IRI	O
should	O
next	O
be	O
encoded	O
as	O
UTF-8	O
,	O
and	O
the	O
resulting	O
bytes	O
percent-encoded	O
,	O
to	O
produce	O
a	O
valid	O
URI	B-Protocol
.	O
</s>
<s>
ASCII	B-Protocol
code	I-Protocol
points	O
that	O
are	O
invalid	O
URI	B-Protocol
characters	O
may	O
be	O
encoded	O
the	O
same	O
way	O
,	O
depending	O
on	O
implementation	O
.	O
</s>
<s>
This	O
conversion	O
is	O
easily	O
reversible	O
;	O
by	O
definition	O
,	O
converting	O
an	O
IRI	O
to	O
an	O
URI	B-Protocol
and	O
back	O
again	O
will	O
yield	O
an	O
IRI	O
that	O
is	O
semantically	O
equivalent	O
to	O
the	O
original	O
IRI	O
,	O
even	O
though	O
it	O
may	O
differ	O
in	O
exact	O
representation	O
.	O
</s>
<s>
Punycode	B-General_Concept
for	O
DNS	B-Protocol
labels	O
.	O
</s>
<s>
There	O
are	O
reasons	O
to	O
see	O
URIs	B-Protocol
displayed	O
in	O
different	O
languages	O
;	O
mostly	O
,	O
it	O
makes	O
it	O
easier	O
for	O
users	O
who	O
are	O
unfamiliar	O
with	O
the	O
Latin	O
(	O
A	O
–	O
Z	O
)	O
alphabet	O
.	O
</s>
<s>
Assuming	O
that	O
it	O
is	O
n't	O
too	O
difficult	O
for	O
anyone	O
to	O
replicate	O
arbitrary	O
Unicode	O
on	O
their	O
keyboards	O
,	O
this	O
can	O
make	O
the	O
URI	B-Protocol
system	O
more	O
accessible	O
.	O
</s>
<s>
Mixing	O
IRIs	O
and	O
ASCII	B-Protocol
URIs	B-Protocol
can	O
make	O
it	O
much	O
easier	O
to	O
execute	O
phishing	O
attacks	O
that	O
trick	O
someone	O
into	O
believing	O
they	O
are	O
on	O
a	O
different	O
site	O
that	O
they	O
really	O
are	O
.	O
</s>
<s>
For	O
example	O
,	O
one	O
can	O
replace	O
an	O
ASCII	B-Protocol
"	O
a	O
"	O
in	O
www.myfictionalbank.com	O
with	O
the	O
Unicode	O
look-alike	O
"	O
α	O
"	O
to	O
give	O
www.myfictionαlbank.com	O
and	O
point	O
that	O
IRI	O
to	O
a	O
malicious	O
site	O
.	O
</s>
<s>
This	O
is	O
known	O
as	O
an	O
IDN	B-General_Concept
homograph	I-General_Concept
attack	I-General_Concept
.	O
</s>
<s>
While	O
a	O
URI	B-Protocol
does	O
not	O
provide	O
people	O
with	O
a	O
way	O
to	O
specify	O
web	O
resources	O
using	O
their	O
own	O
alphabets	O
,	O
an	O
IRI	O
does	O
not	O
make	O
clear	O
how	O
web	O
resources	O
can	O
be	O
accessed	O
with	O
keyboards	O
that	O
are	O
not	O
capable	O
of	O
generating	O
the	O
requisite	O
internationalized	O
characters	O
.	O
</s>
<s>
This	O
means	O
that	O
IRIs	O
are	O
now	O
handled	O
in	O
a	O
way	O
very	O
similar	O
to	O
many	O
other	O
software	O
which	O
might	O
require	O
the	O
use	O
of	O
a	O
non-keyboard	O
input	B-General_Concept
method	I-General_Concept
when	O
dealing	O
with	O
texts	O
in	O
various	O
languages	O
.	O
</s>
