<s>
Letterboxing	B-Operating_System
is	O
an	O
outdoor	O
hobby	O
that	O
combines	O
elements	O
of	O
orienteering	O
,	O
art	O
,	O
and	O
puzzle	O
solving	O
.	O
</s>
<s>
Letterboxers	B-Operating_System
hide	O
small	O
,	O
weatherproof	O
boxes	O
in	O
publicly	O
accessible	O
places	O
(	O
like	O
parks	O
)	O
and	O
distribute	O
clues	O
to	O
finding	O
the	O
box	O
in	O
printed	O
catalogs	O
,	O
on	O
one	O
of	O
several	O
web	O
sites	O
,	O
or	O
by	O
word	O
of	O
mouth	O
.	O
</s>
<s>
Finders	O
make	O
an	O
imprint	O
of	O
the	O
letterbox	O
's	O
stamp	O
in	O
their	O
personal	O
notebook	O
,	O
and	O
leave	O
an	O
impression	O
of	O
their	O
personal	O
signature	O
stamp	O
on	O
the	O
letterbox	O
's	O
"	O
visitors	O
 '	O
book	O
"	O
or	O
"	O
logbook	O
"	O
—	O
as	O
proof	O
of	O
having	O
found	O
the	O
box	O
and	O
letting	O
other	O
letterboxers	B-Operating_System
know	O
who	O
has	O
visited	O
.	O
</s>
<s>
Many	O
letterboxers	B-Operating_System
keep	O
careful	O
track	O
of	O
their	O
"	O
find	O
count	O
"	O
.	O
</s>
<s>
The	O
origin	O
of	O
letterboxing	B-Operating_System
can	O
be	O
traced	O
to	O
Dartmoor	O
,	O
Devon	O
,	O
England	O
in	O
1854	O
.	O
</s>
<s>
From	O
this	O
hikers	O
on	O
the	O
moors	O
began	O
to	O
leave	O
a	O
letter	O
or	O
postcard	O
inside	O
a	O
box	O
along	O
the	O
trail	O
(	O
sometimes	O
addressed	O
to	O
themselves	O
,	O
sometimes	O
a	O
friend	O
or	O
relative	O
)	O
—	O
hence	O
the	O
name	O
"	O
letterboxing	B-Operating_System
"	O
.	O
</s>
<s>
Letterboxing	B-Operating_System
has	O
become	O
a	O
popular	O
sport	O
,	O
with	O
thousands	O
of	O
walkers	O
gathering	O
for	O
'	O
box-hunts	O
'	O
and	O
while	O
in	O
some	O
areas	O
of	O
Dartmoor	O
it	O
is	O
particularly	O
popular	O
amongst	O
children	O
,	O
some	O
of	O
the	O
more	O
difficult	O
to	O
find	O
boxes	O
and	O
tougher	O
terrain	O
are	O
better	O
suited	O
to	O
more	O
experienced	O
adults	O
.	O
</s>
<s>
Interest	O
in	O
letterboxing	B-Operating_System
in	O
the	O
U.S.	O
is	O
generally	O
considered	O
to	O
have	O
started	O
with	O
a	O
feature	O
article	O
in	O
the	O
Smithsonian	O
magazine	O
in	O
April	O
1998	O
.	O
</s>
<s>
Much	O
of	O
the	O
terminology	O
below	O
is	O
associated	O
with	O
letterboxing	B-Operating_System
in	O
the	O
US	O
and	O
would	O
be	O
unfamiliar	O
to	O
UK	O
letterboxers	B-Operating_System
.	O
</s>
<s>
The	O
growing	O
popularity	O
of	O
the	O
somewhat	O
similar	O
activity	O
of	O
geocaching	B-Application
during	O
the	O
2000s	O
has	O
increased	O
interest	O
in	O
letterboxing	B-Operating_System
as	O
well	O
.	O
</s>
<s>
Letterboxers	B-Operating_System
organize	O
events	O
,	O
usually	O
called	O
meets	O
or	O
gatherings	O
.	O
</s>
<s>
Gatherings	O
in	O
the	O
US	O
are	O
usually	O
at	O
parks	O
or	O
places	O
with	O
enough	O
space	O
for	O
a	O
large	O
group	O
of	O
letterboxers	B-Operating_System
to	O
meet	O
up	O
and	O
do	O
exchanges	O
(	O
exchanging	O
of	O
personal	O
stamps	O
and/or	O
personal	O
travelers	O
)	O
,	O
as	O
well	O
as	O
talk	O
and	O
discuss	O
box	O
ideas	O
.	O
</s>
<s>
The	O
clue	O
is	O
given	O
by	O
word	O
of	O
mouth	O
,	O
or	O
typed	O
up	O
,	O
but	O
a	O
letterboxer	B-Operating_System
can	O
only	O
receive	O
the	O
clue	O
from	O
the	O
planter	O
.	O
</s>
<s>
The	O
clue	O
is	O
hidden	O
in	O
another	O
letterbox	O
(	O
similar	O
to	O
clues	O
for	O
a	O
bonus	O
boxes	O
)	O
,	O
but	O
the	O
letterboxer	B-Operating_System
that	O
finds	O
the	O
clue	O
is	O
expected	O
to	O
move	O
the	O
clue	O
to	O
another	O
nearby	O
letterbox	O
.	O
</s>
<s>
A	O
traveling	O
letterbox	O
,	O
it	O
is	O
placed	O
in	O
a	O
traditional	O
letterbox	O
for	O
another	O
letterboxer	B-Operating_System
to	O
find	O
.	O
</s>
<s>
When	O
found	O
,	O
it	O
is	O
stamped	O
just	O
like	O
a	O
traditional	O
letterbox	O
,	O
but	O
is	O
then	O
carried	O
by	O
the	O
letterboxer	B-Operating_System
to	O
the	O
next	O
letterbox	O
they	O
find	O
and	O
then	O
left	O
in	O
that	O
letterbox	O
for	O
the	O
next	O
finder	O
.	O
</s>
<s>
If	O
another	O
letterboxer	B-Operating_System
is	O
met	O
on	O
the	O
trail	O
or	O
at	O
a	O
meet	O
it	O
is	O
attainable	O
if	O
requested	O
.	O
</s>
<s>
In	O
the	O
US	O
this	O
box	O
is	O
usually	O
only	O
attainable	O
if	O
the	O
other	O
letterboxer	B-Operating_System
knows	O
the	O
password	O
or	O
passphrase	O
which	O
is	O
sometimes	O
cryptic	O
,	O
straightforward	O
,	O
almost	O
non-existent	O
,	O
or	O
silly	O
.	O
</s>
<s>
Much	O
like	O
a	O
hitchhiker	O
,	O
except	O
instead	O
of	O
being	O
carried	O
from	O
letterbox	O
to	O
letterbox	O
,	O
a	O
letterboxer	B-Operating_System
passes	O
it	O
to	O
another	O
letterboxer	B-Operating_System
.	O
</s>
<s>
It	O
can	O
be	O
passed	O
in	O
a	O
Personal	O
Traveler	O
,	O
or	O
planted	O
on	O
another	O
letterboxer	B-Operating_System
or	O
their	O
unattended	O
bags	O
on	O
the	O
trails	O
or	O
at	O
gatherings	O
.	O
</s>
<s>
Normally	O
,	O
there	O
are	O
at	O
least	O
one	O
or	O
two	O
hitchhikers	O
in	O
the	O
box	O
at	O
all	O
times	O
,	O
and	O
any	O
letterboxer	B-Operating_System
who	O
takes	O
a	O
hitchhiker	O
out	O
is	O
required	O
to	O
leave	O
a	O
new	O
one	O
in	O
its	O
place	O
.	O
</s>
<s>
A	O
parasite	O
is	O
very	O
much	O
like	O
a	O
hitchhiker	O
except	O
,	O
instead	O
of	O
being	O
carried	O
by	O
a	O
letterboxer	B-Operating_System
between	O
letterboxes	O
on	O
its	O
own	O
,	O
it	O
is	O
carried	O
along	O
with	O
a	O
hitchhiker	O
.	O
</s>
<s>
When	O
a	O
letterboxer	B-Operating_System
joins	O
a	O
parasite	O
to	O
a	O
hitchhiker	O
(	O
"	O
infecting	O
"	O
it	O
)	O
,	O
it	O
is	O
stamped	O
into	O
the	O
hitchhiker	O
.	O
</s>
<s>
The	O
letterboxer	B-Operating_System
that	O
has	O
done	O
the	O
moving	O
also	O
has	O
the	O
choice	O
of	O
sending	O
the	O
parasite	O
along	O
with	O
a	O
different	O
hitchhiker	O
.	O
</s>
<s>
A	O
letterboxer	B-Operating_System
's	O
find	O
count	O
or	O
PFX	O
count	O
is	O
organized	O
as	O
follows	O
:	O
</s>
<s>
The	O
P	O
(	O
"	O
plants	O
"	O
)	O
count	O
is	O
the	O
number	O
of	O
boxes	O
the	O
letterboxer	B-Operating_System
has	O
made	O
and	O
placed	O
.	O
</s>
<s>
The	O
F	O
(	O
"	O
finds	O
"	O
)	O
count	O
is	O
the	O
number	O
of	O
boxes	O
the	O
letterboxer	B-Operating_System
has	O
found	O
in	O
the	O
wild	O
.	O
</s>
<s>
The	O
X	O
(	O
"	O
exchanges	O
"	O
)	O
count	O
is	O
the	O
number	O
of	O
exchanges	O
the	O
letterboxer	B-Operating_System
has	O
.	O
</s>
<s>
Many	O
letterboxers	B-Operating_System
do	O
not	O
bother	O
to	O
keep	O
count	O
at	O
all	O
.	O
</s>
<s>
The	O
"	O
PFX	O
count	O
"	O
is	O
not	O
a	O
term	O
associated	O
with	O
Dartmoor	O
Letterboxing	B-Operating_System
.	O
</s>
<s>
Originally	O
coined	O
in	O
the	O
USA	O
,	O
it	O
is	O
similar	O
to	O
the	O
concept	O
of	O
letterboxing	B-Operating_System
where	O
clues	O
lead	O
to	O
sealed	O
boxes	O
to	O
be	O
found	O
in	O
a	O
type	O
of	O
treasure	O
hunt	O
.	O
</s>
