<s>
A	O
trackback	B-Application
allows	O
one	O
website	O
to	O
notify	O
another	O
about	O
an	O
update	O
.	O
</s>
<s>
It	O
is	O
one	O
of	O
four	O
types	O
of	O
linkback	B-Application
methods	O
for	O
website	O
authors	O
to	O
request	O
notification	O
when	O
somebody	O
links	O
to	O
one	O
of	O
their	O
documents	O
.	O
</s>
<s>
Some	O
weblog	O
software	O
,	O
such	O
as	O
SilverStripe	B-Application
,	O
WordPress	B-Application
,	O
Drupal	B-Application
,	O
and	O
Movable	B-Protocol
Type	I-Protocol
,	O
supports	O
automatic	O
pingbacks	B-Application
where	O
all	O
the	O
links	O
in	O
a	O
published	O
article	O
can	O
be	O
pinged	O
when	O
the	O
article	O
is	O
published	O
.	O
</s>
<s>
The	O
term	O
is	O
used	O
colloquially	O
for	O
any	O
kind	O
of	O
linkback	B-Application
.	O
</s>
<s>
The	O
TrackBack	B-Application
specification	O
was	O
created	O
by	O
Six	B-Protocol
Apart	I-Protocol
,	O
which	O
first	O
implemented	O
it	O
in	O
its	O
Movable	B-Protocol
Type	I-Protocol
blogging	O
software	O
in	O
August	O
2002	O
.	O
</s>
<s>
The	O
TrackBack	B-Application
has	O
since	O
been	O
implemented	O
in	O
most	O
other	O
blogging	O
tools	O
.	O
</s>
<s>
Six	B-Protocol
Apart	I-Protocol
started	O
a	O
working	O
group	O
in	O
February	O
2006	O
to	O
improve	O
the	O
Trackback	B-Application
protocol	O
with	O
the	O
goal	O
to	O
eventually	O
have	O
it	O
approved	O
as	O
an	O
Internet	O
standard	O
by	O
the	O
IETF	O
.	O
</s>
<s>
One	O
notable	O
blogging	O
service	O
that	O
does	O
not	O
support	O
trackback	B-Application
is	O
Blogger	B-Application
.	O
</s>
<s>
Instead	O
,	O
Blogger	B-Application
provides	O
"	O
backlinks	O
"	O
,	O
which	O
allow	O
users	O
to	O
employ	O
Google	O
's	O
search	O
infrastructure	O
to	O
show	O
links	O
between	O
blog	O
entries	O
.	O
</s>
<s>
A	O
trackback	B-Application
is	O
an	O
acknowledgment	O
.	O
</s>
<s>
This	O
acknowledgment	O
is	O
sent	O
via	O
a	O
network	O
signal	O
(	O
XML-RPC	B-Protocol
ping	O
)	O
from	O
the	O
originating	O
site	O
to	O
the	O
receiving	O
site	O
.	O
</s>
<s>
Trackback	B-Application
requires	O
both	O
sites	O
to	O
be	O
trackback-enabled	O
in	O
order	O
to	O
establish	O
this	O
communication	O
.	O
</s>
<s>
Trackbacks	B-Application
are	O
used	O
primarily	O
to	O
facilitate	O
communication	O
between	O
blogs	O
;	O
if	O
a	O
blogger	B-Application
writes	O
a	O
new	O
entry	O
commenting	O
on	O
,	O
or	O
referring	O
to	O
,	O
an	O
entry	O
found	O
at	O
another	O
blog	O
,	O
and	O
both	O
blogging	O
tools	O
support	O
the	O
TrackBack	B-Application
protocol	O
,	O
then	O
the	O
commenting	O
blogger	B-Application
can	O
notify	O
the	O
other	O
blog	O
with	O
a	O
"	O
TrackBack	B-Application
ping	O
"	O
;	O
the	O
receiving	O
blog	O
will	O
typically	O
display	O
summaries	O
of	O
,	O
and	O
links	O
to	O
,	O
all	O
the	O
commenting	O
entries	O
below	O
the	O
original	O
entry	O
.	O
</s>
<s>
Blogging	O
software	O
that	O
supports	O
the	O
TrackBack	B-Application
protocol	O
displays	O
a	O
"	O
TrackBack	B-Application
URL	I-Application
"	O
with	O
every	O
entry	O
.	O
</s>
<s>
This	O
URL	O
is	O
used	O
by	O
the	O
commenting	O
blogger	B-Application
,	O
whose	O
software	O
will	O
send	O
XML-formatted	O
information	O
about	O
the	O
new	O
entry	O
to	O
this	O
URL	O
.	O
</s>
<s>
Some	O
blogging	O
tools	O
are	O
able	O
to	O
discover	O
these	O
TrackBack	B-Application
URLs	I-Application
automatically	O
,	O
others	O
require	O
the	O
commenting	O
blogger	B-Application
to	O
enter	O
them	O
manually	O
.	O
</s>
<s>
Some	O
individuals	O
or	O
companies	O
have	O
abused	O
the	O
TrackBack	B-Application
feature	O
to	O
insert	O
spam	O
links	O
on	O
some	O
blogs	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
TrackBack	B-Application
spam	O
filters	O
similar	O
to	O
those	O
implemented	O
against	O
comment	O
spam	O
now	O
exist	O
in	O
many	O
weblog	O
publishing	O
systems	O
.	O
</s>
<s>
Many	O
blogs	O
have	O
stopped	O
using	O
trackbacks	B-Application
because	O
dealing	O
with	O
spam	O
became	O
too	O
much	O
of	O
a	O
burden	O
.	O
</s>
