<s>
A	O
class	B-Application
hierarchy	I-Application
or	O
inheritance	B-Application
tree	I-Application
in	O
computer	B-General_Concept
science	I-General_Concept
is	O
a	O
classification	O
of	O
object	O
types	O
,	O
denoting	O
objects	O
as	O
the	O
instantiations	O
of	O
classes	O
(	O
class	O
is	O
like	O
a	O
blueprint	O
,	O
the	O
object	O
is	O
what	O
is	O
built	O
from	O
that	O
blueprint	O
)	O
inter-relating	O
the	O
various	O
classes	O
by	O
relationships	O
such	O
as	O
"	O
inherits	O
"	O
,	O
"	O
extends	O
"	O
,	O
"	O
is	O
an	O
abstraction	O
of	O
"	O
,	O
"	O
an	O
interface	O
definition	O
"	O
.	O
</s>
<s>
In	O
object-oriented	B-Language
programming	I-Language
,	O
a	O
class	O
is	O
a	O
template	O
that	O
defines	O
the	O
state	O
and	O
behavior	O
common	O
to	O
objects	O
of	O
a	O
certain	O
kind	O
.	O
</s>
<s>
The	O
concept	O
of	O
class	B-Application
hierarchy	I-Application
in	O
computer	B-General_Concept
science	I-General_Concept
is	O
very	O
similar	O
to	O
taxonomy	O
,	O
the	O
classifications	O
of	O
species	O
.	O
</s>
<s>
The	O
relationships	O
are	O
specified	O
in	O
the	O
science	O
of	O
object-oriented	B-Language
design	O
and	O
object	O
interface	O
standards	O
defined	O
by	O
popular	O
use	O
,	O
language	O
designers	O
(	O
Java	B-Language
,	O
C++	B-Language
,	O
Smalltalk	B-Application
,	O
Visual	B-Application
Prolog	I-Application
)	O
and	O
standards	O
committees	O
for	O
software	O
design	O
like	O
the	O
Object	B-Architecture
Management	I-Architecture
Group	I-Architecture
.	O
</s>
<s>
The	O
class	B-Application
hierarchy	I-Application
can	O
be	O
as	O
deep	O
as	O
needed	O
.	O
</s>
<s>
When	O
a	O
message	O
is	O
sent	O
to	O
an	O
object	O
,	O
it	O
is	O
passed	O
up	O
the	O
inheritance	B-Application
tree	I-Application
starting	O
from	O
the	O
class	O
of	O
the	O
receiving	O
object	O
until	O
a	O
definition	O
is	O
found	O
for	O
the	O
method	O
.	O
</s>
