<s>
In	O
computing	O
,	O
the	O
superuser	B-Application
is	O
a	O
special	O
user	O
account	O
used	O
for	O
system	O
administration	O
.	O
</s>
<s>
In	O
some	O
cases	O
,	O
the	O
actual	O
name	O
of	O
the	O
account	O
is	O
not	O
the	O
determining	O
factor	O
;	O
on	O
Unix-like	B-Operating_System
systems	I-Operating_System
,	O
for	O
example	O
,	O
the	O
user	O
with	O
a	O
user	B-Application
identifier	I-Application
(	O
UID	O
)	O
of	O
zero	O
is	O
the	O
superuser	B-Application
,	O
regardless	O
of	O
the	O
name	O
of	O
that	O
account	O
;	O
and	O
in	O
systems	O
which	O
implement	O
a	O
role	O
based	O
security	O
model	O
,	O
any	O
user	O
with	O
the	O
role	O
of	O
superuser	B-Application
(	O
or	O
its	O
synonyms	O
)	O
can	O
carry	O
out	O
all	O
actions	O
of	O
the	O
superuser	B-Application
account	O
.	O
</s>
<s>
The	O
principle	O
of	O
least	O
privilege	O
recommends	O
that	O
most	O
users	O
and	O
applications	O
run	O
under	O
an	O
ordinary	O
account	O
to	O
perform	O
their	O
work	O
,	O
as	O
a	O
superuser	B-Application
account	O
is	O
capable	O
of	O
making	O
unrestricted	O
,	O
potentially	O
adverse	O
,	O
system-wide	O
changes	O
.	O
</s>
<s>
In	O
Unix-like	B-Operating_System
computer	O
OSes	O
(	O
such	O
as	O
Linux	B-Application
)	O
,	O
root	O
is	O
the	O
conventional	O
name	O
of	O
the	O
user	O
who	O
has	O
all	O
rights	O
or	O
permissions	O
(	O
to	O
all	O
files	O
and	O
programs	O
)	O
in	O
all	O
modes	O
(	O
single	O
-	O
or	O
multi-user	O
)	O
.	O
</s>
<s>
Alternative	O
names	O
include	O
baron	O
in	O
BeOS	B-Application
and	O
avatar	O
on	O
some	O
Unix	B-Application
variants	O
.	O
</s>
<s>
BSD	B-Operating_System
often	O
provides	O
a	O
toor	O
(	O
"	O
root	O
"	O
written	O
backward	O
)	O
account	O
in	O
addition	O
to	O
a	O
root	B-Application
account	I-Application
.	O
</s>
<s>
Regardless	O
of	O
the	O
name	O
,	O
the	O
superuser	B-Application
always	O
has	O
a	O
user	B-Application
ID	I-Application
of	O
0	O
.	O
</s>
<s>
The	O
root	B-Application
user	I-Application
can	O
do	O
many	O
things	O
an	O
ordinary	O
user	O
cannot	O
,	O
such	O
as	O
changing	O
the	O
ownership	O
of	O
files	O
and	O
binding	O
to	O
network	B-Protocol
ports	I-Protocol
numbered	O
below	O
1024	O
.	O
</s>
<s>
The	O
name	O
root	O
may	O
have	O
originated	O
because	O
root	O
is	O
the	O
only	O
user	O
account	O
with	O
permission	O
to	O
modify	O
the	O
root	B-Application
directory	I-Application
of	O
a	O
Unix	B-Application
system	I-Application
.	O
</s>
<s>
This	O
directory	O
was	O
originally	O
considered	O
to	O
be	O
root	O
's	O
home	B-Application
directory	I-Application
,	O
but	O
the	O
UNIX	B-Application
Filesystem	B-Application
Hierarchy	I-Application
Standard	I-Application
now	O
recommends	O
that	O
root	O
's	O
home	O
be	O
at	O
.	O
</s>
<s>
The	O
first	O
process	O
bootstrapped	O
in	O
a	O
Unix-like	B-Operating_System
system	I-Operating_System
,	O
usually	O
called	O
,	O
runs	O
with	O
root	B-Application
privileges	I-Application
.	O
</s>
<s>
Only	O
a	O
process	O
running	O
as	O
root	O
is	O
allowed	O
to	O
change	O
its	O
user	B-Application
ID	I-Application
to	O
that	O
of	O
another	O
user	O
;	O
once	O
it	O
has	O
done	O
so	O
,	O
there	O
is	O
no	O
way	O
back	O
.	O
</s>
<s>
Doing	O
so	O
is	O
sometimes	O
called	O
dropping	O
root	B-Application
privileges	I-Application
and	O
is	O
often	O
done	O
as	O
a	O
security	O
measure	O
to	O
limit	O
the	O
damage	O
from	O
possible	O
contamination	O
of	O
the	O
process	O
.	O
</s>
<s>
The	O
approach	O
requires	O
the	O
user	O
to	O
know	O
the	O
root	B-Application
password	I-Application
,	O
while	O
the	O
method	O
requires	O
that	O
the	O
user	O
be	O
set	O
up	O
with	O
the	O
power	O
to	O
run	O
"	O
as	O
root	O
"	O
within	O
the	O
file	O
,	O
typically	O
indirectly	O
by	O
being	O
made	O
a	O
member	O
of	O
the	O
wheel	O
,	O
adm	O
,	O
admin	O
,	O
or	O
sudo	B-Device
group	O
.	O
</s>
<s>
Some	O
OSes	O
,	O
such	O
as	O
macOS	B-Application
and	O
some	O
Linux	B-Application
distributions	O
(	O
most	O
notably	O
Ubuntu	B-Operating_System
)	O
,	O
automatically	O
give	O
the	O
initial	O
user	O
created	O
the	O
ability	O
to	O
run	O
as	O
root	O
via	O
–	O
but	O
this	O
is	O
configured	O
to	O
ask	O
them	O
for	O
their	O
password	O
before	O
doing	O
administrative	O
actions	O
.	O
</s>
<s>
In	O
some	O
cases	O
the	O
actual	O
root	B-Application
account	I-Application
is	O
disabled	O
by	O
default	O
,	O
so	O
it	O
ca	O
n't	O
be	O
directly	O
used	O
.	O
</s>
<s>
In	O
mobile	O
platform-oriented	O
OSs	O
such	O
as	O
Apple	B-Operating_System
iOS	I-Operating_System
and	O
Android	B-Application
,	O
superuser	B-Application
access	O
is	O
inaccessible	O
by	O
design	O
,	O
but	O
generally	O
the	O
security	O
system	O
can	O
be	O
exploited	O
in	O
order	O
to	O
obtain	O
it	O
.	O
</s>
<s>
In	O
a	O
few	O
systems	O
,	O
such	O
as	O
Plan	B-Operating_System
9	I-Operating_System
,	O
there	O
is	O
no	O
superuser	B-Application
at	O
all	O
.	O
</s>
<s>
In	O
Windows	B-Device
NT	I-Device
and	O
later	O
systems	O
derived	O
from	O
it	O
(	O
such	O
as	O
Windows	B-Application
2000	I-Application
,	O
Windows	B-Application
XP	I-Application
,	O
Windows	B-Application
Server	I-Application
2003	I-Application
,	O
and	O
Windows	O
Vista/7/8/10/11	O
)	O
,	O
there	O
must	O
be	O
at	O
least	O
one	O
administrator	B-Application
account	I-Application
(	O
Windows	B-Application
XP	I-Application
and	O
earlier	O
)	O
or	O
one	O
able	O
to	O
elevate	O
privileges	O
to	O
superuser	B-Application
(	O
Windows	O
Vista/7/8/10/11	O
via	O
User	O
Account	O
Control	O
)	O
.	O
</s>
<s>
In	O
Windows	B-Application
XP	I-Application
and	O
earlier	O
systems	O
,	O
there	O
is	O
a	O
built-in	O
administrator	B-Application
account	I-Application
that	O
remains	O
hidden	O
when	O
a	O
user	O
administrator-equivalent	O
account	O
exists	O
.	O
</s>
<s>
This	O
built-in	O
administrator	B-Application
account	I-Application
is	O
created	O
with	O
a	O
blank	O
password	O
.	O
</s>
<s>
This	O
poses	O
security	O
risks	O
as	O
local	O
users	O
would	O
be	O
able	O
to	O
access	O
the	O
computer	O
via	O
the	O
built-in	O
administrator	B-Application
account	I-Application
if	O
the	O
password	O
is	O
left	O
blank	O
,	O
so	O
the	O
account	O
is	O
disabled	O
by	O
default	O
in	O
Windows	B-Application
Vista	I-Application
and	O
later	O
systems	O
due	O
to	O
the	O
introduction	O
of	O
User	O
Account	O
Control	O
(	O
UAC	O
)	O
.	O
</s>
<s>
Remote	O
users	O
are	O
unable	O
to	O
access	O
the	O
built-in	O
administrator	B-Application
account	I-Application
.	O
</s>
<s>
A	O
Windows	O
administrator	B-Application
account	I-Application
is	O
not	O
an	O
exact	O
analogue	O
of	O
the	O
Unix	B-Application
root	B-Application
account	I-Application
–	O
Administrator	O
,	O
the	O
built-in	O
administrator	B-Application
account	I-Application
,	O
and	O
a	O
user	O
administrator	B-Application
account	I-Application
have	O
the	O
same	O
level	O
of	O
privileges	O
.	O
</s>
<s>
The	O
default	O
user	O
account	O
created	O
in	O
Windows	O
systems	O
is	O
an	O
administrator	B-Application
account	I-Application
.	O
</s>
<s>
Unlike	O
macOS	B-Application
,	O
Linux	B-Application
,	O
and	O
Windows	O
Vista/7/8/10	O
administrator	B-Application
accounts	I-Application
,	O
administrator	B-Application
accounts	I-Application
in	O
Windows	O
systems	O
without	O
UAC	O
do	O
not	O
insulate	O
the	O
system	O
from	O
most	O
of	O
the	O
pitfalls	O
of	O
full	O
root	B-Application
access	I-Application
.	O
</s>
<s>
To	O
avoid	O
this	O
and	O
maintain	O
optimal	O
system	O
security	O
on	O
pre-UAC	O
Windows	O
systems	O
,	O
it	O
is	O
recommended	O
to	O
simply	O
authenticate	O
when	O
necessary	O
from	O
a	O
standard	O
user	O
account	O
,	O
either	O
via	O
a	O
password	O
set	O
to	O
the	O
built-in	O
administrator	B-Application
account	I-Application
,	O
or	O
another	O
administrator	B-Application
account	I-Application
.	O
</s>
<s>
In	O
Windows	O
Vista/7/8/10/11	O
administrator	B-Application
accounts	I-Application
,	O
a	O
prompt	O
will	O
appear	O
to	O
authenticate	O
running	O
a	O
process	O
with	O
elevated	O
privileges	O
.	O
</s>
<s>
Usually	O
,	O
no	O
user	O
credentials	O
are	O
required	O
to	O
authenticate	O
the	O
UAC	O
prompt	O
in	O
administrator	B-Application
accounts	I-Application
but	O
authenticating	O
the	O
UAC	O
prompt	O
requires	O
entering	O
the	O
username	O
and	O
password	O
of	O
an	O
administrator	O
in	O
standard	O
user	O
accounts	O
.	O
</s>
<s>
In	O
Windows	B-Application
XP	I-Application
(	O
and	O
earlier	O
systems	O
)	O
administrator	B-Application
accounts	I-Application
,	O
authentication	O
is	O
not	O
required	O
to	O
run	O
a	O
process	O
with	O
elevated	O
privileges	O
and	O
this	O
poses	O
another	O
security	O
risk	O
that	O
led	O
to	O
the	O
development	O
of	O
UAC	O
.	O
</s>
<s>
Users	O
can	O
set	O
a	O
process	O
to	O
run	O
with	O
elevated	O
privileges	O
from	O
standard	O
accounts	O
by	O
setting	O
the	O
process	O
to	O
"	O
run	O
as	O
administrator	O
"	O
or	O
using	O
the	O
command	O
and	O
authenticating	O
the	O
prompt	O
with	O
credentials	O
(	O
username	O
and	O
password	O
)	O
of	O
an	O
administrator	B-Application
account	I-Application
.	O
</s>
<s>
Much	O
of	O
the	O
benefit	O
of	O
authenticating	O
from	O
a	O
standard	O
account	O
is	O
negated	O
if	O
the	O
administrator	B-Application
account	I-Application
's	O
credentials	O
being	O
used	O
has	O
a	O
blank	O
password	O
(	O
as	O
in	O
the	O
built-in	O
administrator	B-Application
account	I-Application
in	O
Windows	B-Application
XP	I-Application
and	O
earlier	O
systems	O
)	O
,	O
hence	O
why	O
it	O
is	O
recommended	O
to	O
set	O
a	O
password	O
for	O
the	O
built-in	O
administrator	B-Application
account	I-Application
.	O
</s>
<s>
In	O
Windows	B-Device
NT	I-Device
,	O
2000	O
and	O
higher	O
,	O
the	O
root	B-Application
user	I-Application
is	O
the	O
Administrator	B-Application
account	I-Application
.	O
</s>
<s>
In	O
Novell	B-Operating_System
NetWare	I-Operating_System
,	O
the	O
superuser	B-Application
was	O
called	O
"	O
supervisor	O
"	O
,	O
later	O
"	O
admin	O
"	O
.	O
</s>
<s>
In	O
OpenVMS	O
,	O
"	O
SYSTEM	O
"	O
is	O
the	O
superuser	B-Application
account	O
for	O
the	O
OS	O
.	O
</s>
<s>
Many	O
such	O
systems	O
,	O
such	O
as	O
DOS	B-Device
,	O
did	O
not	O
have	O
the	O
concept	O
of	O
multiple	O
accounts	O
,	O
and	O
although	O
others	O
such	O
as	O
Windows	O
95	O
did	O
allow	O
multiple	O
accounts	O
,	O
this	O
was	O
only	O
so	O
that	O
each	O
could	O
have	O
its	O
own	O
preferences	O
profile	O
–	O
all	O
users	O
still	O
had	O
full	O
administrative	O
control	O
over	O
the	O
machine	O
.	O
</s>
