<s>
In	O
computer	B-General_Concept
science	I-General_Concept
,	O
a	O
data	B-General_Concept
structure	I-General_Concept
is	O
a	O
data	O
organization	O
,	O
management	O
,	O
and	O
storage	O
format	O
that	O
is	O
usually	O
chosen	O
for	O
efficient	O
access	B-General_Concept
to	O
data	O
.	O
</s>
<s>
More	O
precisely	O
,	O
a	O
data	B-General_Concept
structure	I-General_Concept
is	O
a	O
collection	O
of	O
data	O
values	O
,	O
the	O
relationships	O
among	O
them	O
,	O
and	O
the	O
functions	O
or	O
operations	O
that	O
can	O
be	O
applied	O
to	O
the	O
data	O
,	O
i.e.	O
,	O
it	O
is	O
an	O
algebraic	O
structure	O
about	O
data	O
.	O
</s>
<s>
Data	B-General_Concept
structures	I-General_Concept
serve	O
as	O
the	O
basis	O
for	O
abstract	O
data	O
types	O
(	O
ADT	O
)	O
.	O
</s>
<s>
The	O
data	B-General_Concept
structure	I-General_Concept
implements	O
the	O
physical	O
form	O
of	O
the	O
data	O
type	O
.	O
</s>
<s>
Different	O
types	B-General_Concept
of	I-General_Concept
data	I-General_Concept
structures	I-General_Concept
are	O
suited	O
to	O
different	O
kinds	O
of	O
applications	O
,	O
and	O
some	O
are	O
highly	O
specialized	O
to	O
specific	O
tasks	O
.	O
</s>
<s>
For	O
example	O
,	O
relational	B-Application
databases	I-Application
commonly	O
use	O
B-tree	B-Architecture
indexes	O
for	O
data	O
retrieval	O
,	O
while	O
compiler	B-Language
implementations	O
usually	O
use	O
hash	B-Algorithm
tables	I-Algorithm
to	O
look	O
up	O
identifiers	O
.	O
</s>
<s>
Data	B-General_Concept
structures	I-General_Concept
provide	O
a	O
means	O
to	O
manage	O
large	O
amounts	O
of	O
data	O
efficiently	O
for	O
uses	O
such	O
as	O
large	O
databases	O
and	O
internet	O
indexing	O
services	O
.	O
</s>
<s>
Usually	O
,	O
efficient	O
data	B-General_Concept
structures	I-General_Concept
are	O
key	O
to	O
designing	O
efficient	O
algorithms	O
.	O
</s>
<s>
Some	O
formal	O
design	O
methods	O
and	O
programming	O
languages	O
emphasize	O
data	B-General_Concept
structures	I-General_Concept
,	O
rather	O
than	O
algorithms	O
,	O
as	O
the	O
key	O
organizing	O
factor	O
in	O
software	O
design	O
.	O
</s>
<s>
Data	B-General_Concept
structures	I-General_Concept
can	O
be	O
used	O
to	O
organize	O
the	O
storage	O
and	O
retrieval	O
of	O
information	O
stored	O
in	O
both	O
main	O
memory	O
and	O
secondary	O
memory	O
.	O
</s>
<s>
Data	B-General_Concept
structures	I-General_Concept
are	O
generally	O
based	O
on	O
the	O
ability	O
of	O
a	O
computer	O
to	O
fetch	O
and	O
store	O
data	O
at	O
any	O
place	O
in	O
its	O
memory	O
,	O
specified	O
by	O
a	O
pointer	O
—	O
a	O
bit	O
string	O
,	O
representing	O
a	O
memory	B-General_Concept
address	I-General_Concept
,	O
that	O
can	O
be	O
itself	O
stored	O
in	O
memory	O
and	O
manipulated	O
by	O
the	O
program	O
.	O
</s>
<s>
Thus	O
,	O
the	O
array	B-Data_Structure
and	O
record	O
data	B-General_Concept
structures	I-General_Concept
are	O
based	O
on	O
computing	O
the	O
addresses	O
of	O
data	O
items	O
with	O
arithmetic	O
operations	O
,	O
while	O
the	O
linked	B-Application
data	I-Application
structures	I-Application
are	O
based	O
on	O
storing	O
addresses	O
of	O
data	O
items	O
within	O
the	O
structure	O
itself	O
.	O
</s>
<s>
The	O
implementation	O
of	O
a	O
data	B-General_Concept
structure	I-General_Concept
usually	O
requires	O
writing	O
a	O
set	O
of	O
procedures	O
that	O
create	O
and	O
manipulate	O
instances	O
of	O
that	O
structure	O
.	O
</s>
<s>
The	O
efficiency	O
of	O
a	O
data	B-General_Concept
structure	I-General_Concept
cannot	O
be	O
analyzed	O
separately	O
from	O
those	O
operations	O
.	O
</s>
<s>
This	O
observation	O
motivates	O
the	O
theoretical	O
concept	O
of	O
an	O
abstract	O
data	O
type	O
,	O
a	O
data	B-General_Concept
structure	I-General_Concept
that	O
is	O
defined	O
indirectly	O
by	O
the	O
operations	O
that	O
may	O
be	O
performed	O
on	O
it	O
,	O
and	O
the	O
mathematical	O
properties	O
of	O
those	O
operations	O
(	O
including	O
their	O
space	O
and	O
time	O
cost	O
)	O
.	O
</s>
<s>
There	O
are	O
numerous	O
types	B-General_Concept
of	I-General_Concept
data	I-General_Concept
structures	I-General_Concept
,	O
generally	O
built	O
upon	O
simpler	O
primitive	O
data	O
types	O
.	O
</s>
<s>
An	O
array	B-Data_Structure
is	O
a	O
number	O
of	O
elements	O
in	O
a	O
specific	O
order	O
,	O
typically	O
all	O
of	O
the	O
same	O
type	O
(	O
depending	O
on	O
the	O
language	O
,	O
individual	O
elements	O
may	O
either	O
all	O
be	O
forced	O
to	O
be	O
the	O
same	O
type	O
,	O
or	O
may	O
be	O
of	O
almost	O
any	O
type	O
)	O
.	O
</s>
<s>
A	O
linked	B-Data_Structure
list	I-Data_Structure
(	O
also	O
just	O
called	O
list	O
)	O
is	O
a	O
linear	O
collection	O
of	O
data	O
elements	O
of	O
any	O
type	O
,	O
called	O
nodes	O
,	O
where	O
each	O
node	O
has	O
itself	O
a	O
value	O
,	O
and	O
points	O
to	O
the	O
next	O
node	O
in	O
the	O
linked	B-Data_Structure
list	I-Data_Structure
.	O
</s>
<s>
The	O
principal	O
advantage	O
of	O
a	O
linked	B-Data_Structure
list	I-Data_Structure
over	O
an	O
array	B-Data_Structure
is	O
that	O
values	O
can	O
always	O
be	O
efficiently	O
inserted	O
and	O
removed	O
without	O
relocating	O
the	O
rest	O
of	O
the	O
list	O
.	O
</s>
<s>
Certain	O
other	O
operations	O
,	O
such	O
as	O
random	B-General_Concept
access	I-General_Concept
to	O
a	O
certain	O
element	O
,	O
are	O
however	O
slower	O
on	O
lists	O
than	O
on	O
arrays	O
.	O
</s>
<s>
A	O
record	O
(	O
also	O
called	O
tuple	O
or	O
struct	O
)	O
is	O
an	O
aggregate	O
data	B-General_Concept
structure	I-General_Concept
.	O
</s>
<s>
In	O
the	O
context	O
of	O
object-oriented	B-Language
programming	I-Language
,	O
records	O
are	O
known	O
as	O
plain	B-Language
old	I-Language
data	I-Language
structures	I-Language
to	O
distinguish	O
them	O
from	O
objects	O
.	O
</s>
<s>
Hash	B-Algorithm
tables	I-Algorithm
,	O
graphs	B-Application
,	O
stacks	B-Application
,	O
queues	B-Application
,	O
trees	B-Application
,	O
binary	O
trees	B-Application
and	O
tries	B-General_Concept
.	O
</s>
<s>
Most	O
assembly	B-Language
languages	I-Language
and	O
some	O
low-level	B-Language
languages	I-Language
,	O
such	O
as	O
BCPL	B-Language
(	O
Basic	B-Language
Combined	I-Language
Programming	I-Language
Language	I-Language
)	O
,	O
lack	O
built-in	O
support	O
for	O
data	B-General_Concept
structures	I-General_Concept
.	O
</s>
<s>
On	O
the	O
other	O
hand	O
,	O
many	O
high-level	B-Language
programming	I-Language
languages	I-Language
and	O
some	O
higher-level	O
assembly	B-Language
languages	I-Language
,	O
such	O
as	O
MASM	B-Application
,	O
have	O
special	O
syntax	O
or	O
other	O
built-in	O
support	O
for	O
certain	O
data	B-General_Concept
structures	I-General_Concept
,	O
such	O
as	O
records	O
and	O
arrays	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
C	B-Language
(	O
a	O
direct	O
descendant	O
of	O
BCPL	B-Language
)	O
and	O
Pascal	B-Application
languages	I-Application
support	O
structs	O
and	O
records	O
,	O
respectively	O
,	O
in	O
addition	O
to	O
vectors	O
(	O
one-dimensional	O
arrays	O
)	O
and	O
multi-dimensional	O
arrays	O
.	O
</s>
<s>
Most	O
programming	O
languages	O
feature	O
some	O
sort	O
of	O
library	B-Library
mechanism	O
that	O
allows	O
data	B-General_Concept
structure	I-General_Concept
implementations	O
to	O
be	O
reused	O
by	O
different	O
programs	O
.	O
</s>
<s>
Modern	O
languages	O
usually	O
come	O
with	O
standard	O
libraries	O
that	O
implement	O
the	O
most	O
common	O
data	B-General_Concept
structures	I-General_Concept
.	O
</s>
<s>
Examples	O
are	O
the	O
C++	B-Language
Standard	B-Application
Template	I-Application
Library	I-Application
,	O
the	O
Java	B-Language
Collections	I-Language
Framework	I-Language
,	O
and	O
the	O
Microsoft	B-Application
.NET	I-Application
Framework	I-Application
.	O
</s>
<s>
Modern	O
languages	O
also	O
generally	O
support	O
modular	B-Architecture
programming	I-Architecture
,	O
the	O
separation	O
between	O
the	O
interface	B-Application
of	O
a	O
library	B-Library
module	B-Architecture
and	O
its	O
implementation	O
.	O
</s>
<s>
Some	O
provide	O
opaque	B-General_Concept
data	I-General_Concept
types	I-General_Concept
that	O
allow	O
clients	O
to	O
hide	O
implementation	O
details	O
.	O
</s>
<s>
Object-oriented	B-Language
programming	I-Language
languages	I-Language
,	O
such	O
as	O
C++	B-Language
,	O
Java	B-Language
,	O
and	O
Smalltalk	B-Application
,	O
typically	O
use	O
classes	O
for	O
this	O
purpose	O
.	O
</s>
<s>
Many	O
known	O
data	B-General_Concept
structures	I-General_Concept
have	O
concurrent	B-Operating_System
versions	O
which	O
allow	O
multiple	O
computing	O
threads	O
to	O
access	B-General_Concept
a	O
single	O
concrete	O
instance	O
of	O
a	O
data	B-General_Concept
structure	I-General_Concept
simultaneously	O
.	O
</s>
