<s>
Data	B-Application
hierarchy	I-Application
refers	O
to	O
the	O
systematic	O
organization	O
of	O
data	O
,	O
often	O
in	O
a	O
hierarchical	O
form	O
.	O
</s>
<s>
"	O
Data	B-Application
hierarchy	I-Application
"	O
is	O
a	O
basic	O
concept	O
in	O
data	O
and	O
database	B-General_Concept
theory	I-General_Concept
and	O
helps	O
to	O
show	O
the	O
relationships	O
between	O
smaller	O
and	O
larger	O
components	O
in	O
a	O
database	O
or	O
data	O
file	B-Operating_System
.	O
</s>
<s>
It	O
is	O
particularly	O
important	O
in	O
databases	O
with	O
referential	B-General_Concept
integrity	I-General_Concept
,	O
third	O
normal	O
form	O
,	O
or	O
perfect	O
key	O
.	O
</s>
<s>
"	O
Data	B-Application
hierarchy	I-Application
"	O
is	O
the	O
result	O
of	O
proper	O
arrangement	O
of	O
data	O
without	O
redundancy	O
.	O
</s>
<s>
Avoiding	O
redundancy	O
eventually	O
leads	O
to	O
proper	O
"	O
data	B-Application
hierarchy	I-Application
"	O
representing	O
the	O
relationship	O
between	O
data	O
,	O
and	O
revealing	O
its	O
relational	O
structure	O
.	O
</s>
<s>
The	O
components	O
of	O
the	O
data	B-Application
hierarchy	I-Application
are	O
listed	O
below	O
.	O
</s>
<s>
A	O
data	B-Application
field	I-Application
holds	O
a	O
single	O
fact	O
or	O
attribute	O
of	O
an	O
entity	O
.	O
</s>
<s>
A	O
file	B-Operating_System
is	O
a	O
collection	O
of	O
related	O
records	O
.	O
</s>
<s>
called	O
Employee	O
Personal	O
Details	O
record	O
)	O
and	O
the	O
collection	O
of	O
100	O
such	O
records	O
would	O
constitute	O
a	O
file	B-Operating_System
(	O
in	O
this	O
case	O
,	O
called	O
Employee	O
Personal	O
Details	O
file	B-Operating_System
)	O
.	O
</s>
<s>
If	O
there	O
are	O
other	O
facets	O
of	O
employee	O
data	O
that	O
we	O
wish	O
to	O
capture	O
,	O
then	O
other	O
files	O
such	O
as	O
Employee	O
Training	O
History	O
file	B-Operating_System
and	O
Employee	O
Work	O
History	O
file	B-Operating_System
could	O
be	O
created	O
as	O
well	O
.	O
</s>
<s>
The	O
above	O
structure	O
can	O
be	O
seen	O
in	O
the	O
hierarchical	B-General_Concept
model	I-General_Concept
,	O
which	O
is	O
one	O
way	O
to	O
organize	O
data	O
in	O
a	O
database	O
.	O
</s>
<s>
In	O
terms	O
of	O
data	O
storage	O
,	O
data	B-Application
fields	I-Application
are	O
made	O
of	O
bytes	B-Application
and	O
these	O
in	O
turn	O
are	O
made	O
up	O
of	O
bits	O
.	O
</s>
