<s>
In	O
e-commerce	O
,	O
the	O
conversion	B-Protocol
funnel	I-Protocol
is	O
the	O
journey	O
a	O
consumer	O
takes	O
through	O
an	O
Internet	O
advertising	O
or	O
search	O
system	O
,	O
navigating	O
an	O
e-commerce	O
website	O
,	O
and	O
finally	O
making	O
a	O
purchase	O
.	O
</s>
<s>
A	O
funnel	B-Operating_System
describes	O
the	O
progressive	O
reduction	O
in	O
the	O
number	O
of	O
users	O
at	O
each	O
stage	O
of	O
the	O
process	O
.	O
</s>
<s>
Advertising	O
efforts	O
can	O
be	O
aimed	O
at	O
"	O
upper	O
funnel	B-Operating_System
"	O
,	O
"	O
middle	O
funnel	B-Operating_System
"	O
,	O
or	O
"	O
lower	O
funnel	B-Operating_System
"	O
potential	O
customers	O
.	O
</s>
<s>
Typically	O
a	O
large	O
number	O
of	O
customers	O
search	O
for	O
a	O
product/service	O
or	O
register	O
as	O
page	O
view	O
on	O
a	O
referring	B-Protocol
page	I-Protocol
which	O
is	O
linked	O
to	O
the	O
e-commerce	O
site	O
by	O
a	O
banner	O
ad	O
,	O
ad	O
network	O
or	O
conventional	O
link	O
.	O
</s>
<s>
The	O
metric	O
used	O
to	O
describe	O
this	O
ratio	O
is	O
the	O
click-through	O
rate	O
(	O
CTR	O
)	O
and	O
represents	O
the	O
top	O
level	O
of	O
the	O
funnel	B-Operating_System
.	O
</s>
<s>
Once	O
the	O
link	O
is	O
clicked	O
and	O
the	O
visitor	O
to	O
the	O
referring	B-Protocol
page	I-Protocol
enters	O
the	O
e-commerce	O
site	O
itself	O
,	O
only	O
a	O
small	O
proportion	O
of	O
visitors	O
typically	O
proceed	O
to	O
the	O
product	O
pages	O
,	O
creating	O
further	O
constriction	O
of	O
the	O
metaphorical	O
funnel	B-Operating_System
.	O
</s>
<s>
Adding	O
the	O
product	O
to	O
the	O
shopping	O
cart	O
,	O
registering	O
or	O
filling	O
in	O
contact	O
details	O
and	O
payment	O
all	O
further	O
reduce	O
the	O
numbers	O
step-by-step	O
cumulatively	O
along	O
the	O
funnel	B-Operating_System
.	O
</s>
