<s>
Yo	B-Application
was	O
a	O
social	O
mobile	B-Application
application	I-Application
for	O
iOS	B-Application
,	O
Android	B-Application
,	O
and	O
formerly	O
also	O
Windows	B-Protocol
Phone	I-Protocol
.	O
</s>
<s>
Initially	O
,	O
the	O
application	O
's	O
only	O
function	O
was	O
to	O
send	O
the	O
user	O
's	O
friends	O
the	O
word	O
"	O
yo	B-Application
"	O
as	O
a	O
text	O
and	O
audio	O
notification	O
,	O
but	O
it	O
has	O
since	O
been	O
updated	O
to	O
enable	O
users	O
to	O
attach	O
links	O
and	O
location	O
to	O
their	O
"	O
Yo	B-Application
"	O
s	O
.	O
</s>
<s>
Yo	B-Application
was	O
created	O
by	O
Israeli	O
developer	O
Or	B-Application
Arbel	I-Application
in	O
eight	O
hours	O
at	O
the	O
request	O
of	O
Moshe	O
Hogeg	O
,	O
CEO	O
of	O
Mobli	B-Algorithm
,	O
who	O
asked	O
Arbel	O
to	O
design	O
a	O
single-button	O
app	O
to	O
send	O
a	O
notification	O
to	O
his	O
assistant	O
or	O
wife	O
.	O
</s>
<s>
It	O
was	O
launched	O
on	O
April	O
Fools	O
 '	O
Day	O
2014	O
for	O
Android	B-Application
and	O
iOS	B-Application
,	O
though	O
initially	O
rejected	O
by	O
Apple	O
for	O
being	O
too	O
simple	O
.	O
</s>
<s>
The	O
app	O
was	O
only	O
shared	O
with	O
Mobli	B-Algorithm
employees	O
to	O
start	O
,	O
however	O
20,000	O
people	O
were	O
using	O
the	O
app	O
within	O
the	O
first	O
month	O
of	O
release	O
.	O
</s>
<s>
The	O
app	O
was	O
shared	O
on	O
the	O
Product	B-Operating_System
Hunt	I-Operating_System
website	O
,	O
through	O
which	O
it	O
exploded	O
in	O
popularity	O
.	O
</s>
<s>
In	O
July	O
2014	O
the	O
app	O
was	O
also	O
released	O
for	O
Windows	B-Protocol
Phone	I-Protocol
.	O
</s>
<s>
Arbel	O
stated	O
interest	O
in	O
expanding	O
the	O
app	O
to	O
include	O
more	O
functionality	O
,	O
including	O
a	O
possible	O
feature	O
which	O
could	O
be	O
used	O
by	O
bloggers	B-Application
to	O
send	O
their	O
followers	O
a	O
'	O
yo	B-Application
 '	O
with	O
a	O
link	O
to	O
the	O
blog	O
attached	O
whenever	O
they	O
post	O
an	O
update	O
;	O
the	O
feature	O
has	O
since	O
been	O
implemented	O
.	O
</s>
<s>
On	O
20	O
June	O
2014	O
,	O
Isaiah	O
Turner	O
hacked	O
the	O
app	O
,	O
allowing	O
him	O
to	O
retrieve	O
any	O
user	O
's	O
phone	O
number	O
and	O
spam/spoof	O
'	O
Yo	B-Application
's	O
to	O
any	O
user	O
.	O
</s>
<s>
In	O
June	O
2015	O
,	O
Yo	B-Application
released	O
the	O
second	O
version	O
of	O
their	O
app	O
with	O
a	O
number	O
of	O
new	O
features	O
.	O
</s>
<s>
The	O
new	O
version	O
also	O
enabled	O
users	O
to	O
collect	O
their	O
friends	O
into	O
groups	O
so	O
that	O
they	O
could	O
"	O
Yo	B-Application
"	O
a	O
number	O
of	O
people	O
with	O
1	O
tap	O
.	O
</s>
<s>
In	O
2016	O
the	O
Yo	B-Application
company	O
shut	O
down	O
.	O
</s>
<s>
The	O
app	O
enables	O
users	O
to	O
send	O
individual	O
notifications	O
to	O
other	O
users	O
,	O
simply	O
containing	O
the	O
word	O
"	O
Yo	B-Application
"	O
.	O
</s>
<s>
Yo	B-Application
is	O
an	O
option	O
for	O
the	O
IFTTT	B-Application
service	O
.	O
</s>
<s>
The	O
app	O
has	O
an	O
API	O
,	O
which	O
has	O
enabled	O
developers	O
and	O
brands	O
to	O
send	O
a	O
Yo	B-Application
to	O
groups	O
of	O
users	O
,	O
such	O
as	O
when	O
the	O
World	O
Cup	O
sent	O
a	O
Yo	B-Application
every	O
time	O
a	O
goal	O
was	O
scored	O
.	O
</s>
<s>
FedEx	O
set	O
up	O
a	O
service	O
using	O
the	O
app	O
through	O
which	O
users	O
could	O
receive	O
a	O
Yo	B-Application
when	O
their	O
package	O
was	O
being	O
delivered	O
.	O
</s>
<s>
Since	O
its	O
release	O
,	O
Yo	B-Application
has	O
been	O
downloaded	O
over	O
3	O
million	O
times	O
and	O
by	O
2016	O
over	O
100	O
million	O
'	O
Yo	B-Application
's	O
had	O
been	O
sent	O
.	O
</s>
<s>
At	O
the	O
height	O
of	O
its	O
popularity	O
the	O
app	O
reached	O
the	O
number	O
4	O
position	O
on	O
the	O
iOS	B-Application
App	I-Application
Store	I-Application
and	O
#1	O
in	O
the	O
social	O
networking	O
category	O
.	O
</s>
<s>
A	O
number	O
of	O
apps	O
inspired	O
by	O
Yo	B-Application
have	O
been	O
released	O
,	O
including	O
one	O
which	O
sends	O
the	O
word	O
'	O
Hodor	O
 '	O
,	O
and	O
one	O
which	O
sends	O
the	O
Indian	O
word	O
'	O
aiyo	O
 '	O
.	O
</s>
<s>
An	O
app	O
called	O
Lo	O
was	O
partly	O
inspired	O
by	O
Yo	B-Application
,	O
sending	O
only	O
a	O
user	O
's	O
location	O
.	O
</s>
<s>
In	O
July	O
2014	O
some	O
of	O
the	O
copies	O
and	O
parodies	O
received	O
copyright	O
complaints	O
from	O
Yo	B-Application
,	O
with	O
Arbel	O
saying	O
"	O
Yo	B-Application
has	O
spawned	O
many	O
clones	O
...	O
some	O
of	O
them	O
are	O
a	O
complete	O
replication	O
of	O
the	O
Yo	B-Application
app	O
...	O
</s>
<s>
In	O
August	O
2014	O
,	O
Tom	O
Scott	O
and	O
Matt	O
Gray	O
created	O
Emojli	B-Protocol
,	O
an	O
emoji	O
only	O
messenger	O
app	O
,	O
partly	O
inspired	O
by	O
the	O
success	O
of	O
Yo	B-Application
.	O
</s>
