<s>
A	O
game	B-Application
server	I-Application
(	O
also	O
sometimes	O
referred	O
to	O
as	O
a	O
host	O
)	O
is	O
a	O
server	B-Application
which	O
is	O
the	O
authoritative	O
source	O
of	O
events	O
in	O
a	O
multiplayer	O
video	O
game	O
.	O
</s>
<s>
The	O
server	B-Application
transmits	O
enough	O
data	O
about	O
its	O
internal	O
state	O
to	O
allow	O
its	O
connected	O
clients	B-Protocol
to	O
maintain	O
their	O
own	O
accurate	O
version	O
of	O
the	O
game	O
world	O
for	O
display	O
to	O
players	O
.	O
</s>
<s>
They	O
also	O
receive	O
and	O
process	B-Operating_System
each	O
player	O
's	O
input	O
.	O
</s>
<s>
Players	O
must	O
connect	O
to	O
the	O
server	B-Application
with	O
separate	O
client	B-Protocol
programs	I-Protocol
in	O
order	O
to	O
see	O
and	O
interact	O
with	O
the	O
game	O
.	O
</s>
<s>
The	O
foremost	O
advantage	O
of	O
dedicated	O
servers	O
is	O
their	O
suitability	O
for	O
hosting	O
in	O
professional	O
data	B-Operating_System
centers	I-Operating_System
,	O
with	O
all	O
of	O
the	O
reliability	O
and	O
performance	O
benefits	O
that	O
entails	O
.	O
</s>
<s>
Remote	O
hosting	O
also	O
eliminates	O
the	O
low-latency	B-Application
advantage	O
that	O
would	O
otherwise	O
be	O
held	O
by	O
any	O
player	O
who	O
hosts	O
and	O
connects	O
to	O
a	O
server	B-Application
from	O
the	O
same	O
machine	O
or	O
local	O
network	O
.	O
</s>
<s>
Cost	O
is	O
sometimes	O
met	O
by	O
a	O
game	O
's	O
developers	O
(	O
particularly	O
on	O
consoles	B-Device
)	O
and	O
sometimes	O
by	O
clan	O
groups	O
,	O
but	O
in	O
either	O
case	O
,	O
the	O
public	O
is	O
reliant	O
on	O
third	O
parties	O
providing	O
servers	O
to	O
connect	O
to	O
.	O
</s>
<s>
For	O
this	O
reason	O
,	O
most	O
games	O
which	O
use	O
dedicated	O
servers	O
also	O
provide	O
listen	B-Application
server	I-Application
support	O
.	O
</s>
<s>
Players	O
of	O
these	O
games	O
will	O
oftentimes	O
host	O
servers	O
for	O
the	O
public	O
and	O
their	O
clans	O
,	O
either	O
by	O
hosting	O
a	O
server	B-Application
instance	O
from	O
their	O
own	O
hardware	O
,	O
or	O
by	O
renting	O
from	O
a	O
game	B-Application
server	I-Application
hosting	I-Application
provider	O
.	O
</s>
<s>
Listen	B-Application
servers	I-Application
run	O
in	O
the	O
same	O
process	B-Operating_System
as	O
a	O
game	O
client	O
.	O
</s>
<s>
Performance	O
is	O
also	O
reduced	O
by	O
the	O
simple	O
fact	O
that	O
the	O
machine	O
running	O
the	O
server	B-Application
is	O
also	O
generating	O
an	O
output	O
image	O
.	O
</s>
<s>
Furthermore	O
,	O
listen	B-Application
servers	I-Application
grant	O
anyone	O
playing	O
on	O
them	O
directly	O
a	O
large	O
latency	B-Application
advantage	O
over	O
other	O
players	O
and	O
cease	O
to	O
exist	O
when	O
that	O
player	O
leaves	O
the	O
game	O
.	O
</s>
<s>
However	O
,	O
listen	B-Application
servers	I-Application
have	O
the	O
advantage	O
of	O
being	O
essentially	O
free	O
and	O
not	O
requiring	O
any	O
special	O
infrastructure	O
or	O
forward	O
planning	O
to	O
set	O
up	O
,	O
which	O
makes	O
them	O
common	O
at	O
LAN	O
parties	O
where	O
latency	B-Application
and	O
bandwidth	O
issues	O
are	O
not	O
a	O
concern	O
.	O
</s>
<s>
They	O
are	O
also	O
common	O
in	O
console	B-Device
games	O
.	O
</s>
<s>
In	O
a	O
listen	B-Application
server	I-Application
arrangement	O
,	O
"	O
host	O
migration	O
"	O
is	O
a	O
useful	O
feature	O
.	O
</s>
<s>
)	O
,	O
the	O
current	O
server	B-Application
stops	O
functioning	O
and	O
gameplay	O
ends	O
.	O
</s>
<s>
In	O
the	O
client/server	O
model	O
outlined	O
elsewhere	O
in	O
this	O
article	O
,	O
clients	B-Protocol
receive	O
processed	O
data	O
from	O
the	O
server	B-Application
and	O
display	O
it	O
without	O
much	O
thought	O
.	O
</s>
<s>
In	O
the	O
alternative	O
"	O
peer-to-peer	O
"	O
model	O
there	O
is	O
no	O
server	B-Application
:	O
each	O
"	O
peer	O
"	O
instead	O
receives	O
the	O
raw	O
input	O
streams	O
of	O
each	O
other	O
player	O
and	O
determines	O
the	O
results	O
itself	O
.	O
</s>
<s>
Each	O
peer	O
must	O
wait	O
for	O
every	O
other	O
peer	O
's	O
message	O
before	O
simulating	O
the	O
next	O
"	O
network	O
frame	O
"	O
,	O
resulting	O
in	O
all	O
players	O
experiencing	O
the	O
same	O
latency	B-Application
as	O
the	O
player	O
with	O
the	O
worst	O
connection	O
.	O
</s>
<s>
Multiple	O
listen	B-Application
servers	I-Application
collectively	O
peer	O
amongst	O
themselves	O
for	O
listen-peer	O
setting	O
.	O
</s>
<s>
This	O
type	O
of	O
setting	O
avoids	O
the	O
disadvantages	O
of	O
peer-to-peer	O
communications	O
among	O
all	O
clients	B-Protocol
and	O
is	O
a	O
better	O
alternative	O
to	O
dedicated	O
servers	O
for	O
increased	O
number	O
of	O
clients	B-Protocol
.	O
</s>
<s>
The	O
rate	O
at	O
which	O
a	O
game	B-Application
server	I-Application
runs	O
simulation	O
steps	O
is	O
commonly	O
referred	O
to	O
as	O
its	O
"	O
tickrate	O
"	O
.	O
</s>
<s>
A	O
"	O
tick	O
"	O
is	O
a	O
number	O
associated	O
with	O
each	O
simulation	O
step	O
which	O
is	O
broadcast	O
to	O
clients	B-Protocol
to	O
help	O
them	O
synchronise	O
with	O
the	O
server	B-Application
.	O
</s>
<s>
There	O
are	O
three	O
reasons	O
to	O
limit	O
the	O
frequency	O
of	O
server	B-Application
simulation	O
steps	O
to	O
a	O
predefined	O
tickrate	O
:	O
to	O
conserve	O
server	B-Application
and	O
client	O
bandwidth	O
,	O
to	O
conserve	O
server	B-Application
CPU	O
time	O
,	O
and	O
to	O
allow	O
clients	B-Protocol
to	O
be	O
certain	O
of	O
how	O
much	O
time	O
has	O
elapsed	O
between	O
each	O
tick	O
.	O
</s>
<s>
The	O
last	O
point	O
is	O
important	O
for	O
internet	O
games	O
,	O
as	O
network	O
updates	O
from	O
the	O
server	B-Application
can	O
arrive	O
at	O
different	O
intervals	O
or	O
even	O
an	O
incorrect	O
order	O
.	O
</s>
<s>
Servers	O
,	O
particularly	O
those	O
of	O
PC	O
games	O
,	O
can	O
generally	O
be	O
customized	O
in	O
ways	O
that	O
still	O
allow	O
unaltered	O
clients	B-Protocol
to	O
connect	O
to	O
them	O
.	O
</s>
<s>
These	O
customizations	O
can	O
include	O
tweaks	O
to	O
built-in	O
game	O
settings	O
,	O
content	O
that	O
is	O
downloaded	O
by	O
clients	B-Protocol
when	O
they	O
join	O
the	O
game	O
,	O
and	O
new	O
code	O
which	O
changes	O
the	O
way	O
that	O
the	O
server	B-Application
behaves	O
.	O
</s>
<s>
While	O
server	B-Application
customization	O
is	O
popular	O
with	O
server	B-Application
administrators	O
and	O
players	O
,	O
it	O
can	O
be	O
at	O
odds	O
with	O
the	O
desire	O
of	O
developers	O
and	O
other	O
players	O
for	O
the	O
game	O
to	O
be	O
experienced	O
as	O
intended	O
.	O
</s>
<s>
It	O
can	O
also	O
aggravate	O
players	O
by	O
enabling	O
abusive	O
administrators	O
to	O
lie	O
about	O
what	O
their	O
server	B-Application
offers	O
.	O
</s>
