<s>
In	O
class-based	B-Application
,	O
object-oriented	B-Language
programming	I-Language
,	O
an	O
instance	B-Application
variable	I-Application
is	O
a	O
variable	O
defined	O
in	O
a	O
class	O
(	O
i.e.	O
,	O
a	O
member	B-Application
variable	I-Application
)	O
,	O
for	O
which	O
each	O
instantiated	O
object	O
of	O
the	O
class	O
has	O
a	O
separate	O
copy	O
,	O
or	O
instance	O
.	O
</s>
<s>
An	O
instance	B-Application
variable	I-Application
has	O
similarities	O
with	O
a	O
class	B-Application
variable	I-Application
,	O
but	O
is	O
non-static	O
.	O
</s>
<s>
An	O
instance	B-Application
variable	I-Application
is	O
a	O
variable	O
which	O
is	O
declared	O
in	O
a	O
class	O
but	O
outside	O
of	O
constructors	O
,	O
methods	O
,	O
or	O
blocks	O
.	O
</s>
<s>
Instance	B-Application
variables	I-Application
are	O
created	O
when	O
an	O
object	O
is	O
instantiated	O
,	O
and	O
are	O
accessible	O
to	O
all	O
the	O
constructors	O
,	O
methods	O
,	O
or	O
blocks	O
in	O
the	O
class	O
.	O
</s>
<s>
Access	O
modifiers	O
can	O
be	O
given	O
to	O
the	O
instance	B-Application
variable	I-Application
.	O
</s>
<s>
An	O
instance	B-Application
variable	I-Application
is	O
not	O
a	O
class	B-Application
variable	I-Application
,	O
although	O
there	O
are	O
similarities	O
.	O
</s>
<s>
It	O
is	O
a	O
type	O
of	O
class	O
attribute	O
(	O
or	O
class	O
property	O
,	O
field	B-Application
,	O
or	O
data	B-Application
member	I-Application
)	O
.	O
</s>
<s>
The	O
same	O
dichotomy	O
between	O
instance	O
and	O
class	O
members	O
applies	O
to	O
methods	O
(	O
"	O
member	O
functions	O
"	O
)	O
as	O
well	O
;	O
a	O
class	O
may	O
have	O
both	O
instance	B-Language
methods	I-Language
and	O
class	B-Application
methods	I-Application
.	O
</s>
<s>
Each	O
instance	B-Application
variable	I-Application
lives	O
in	O
memory	B-General_Concept
for	O
the	O
lifetime	O
of	O
the	O
object	O
it	O
is	O
owned	O
by	O
.	O
</s>
<s>
All	O
instances	O
of	O
an	O
object	O
have	O
their	O
own	O
copies	O
of	O
instance	B-Application
variables	I-Application
,	O
even	O
if	O
the	O
value	O
is	O
the	O
same	O
from	O
one	O
object	O
to	O
another	O
.	O
</s>
<s>
One	O
object	O
instance	O
can	O
change	O
values	O
of	O
its	O
instance	B-Application
variables	I-Application
without	O
affecting	O
all	O
other	O
instances	O
.	O
</s>
<s>
Instance	B-Application
variables	I-Application
can	O
be	O
used	O
by	O
all	O
methods	O
of	O
a	O
class	O
unless	O
the	O
method	B-Language
is	O
declared	O
as	O
static	B-General_Concept
.	O
</s>
<s>
In	O
this	O
C++	B-Language
example	O
,	O
the	O
instance	B-Application
variable	I-Application
Request::number	O
is	O
a	O
copy	O
of	O
the	O
class	B-Application
variable	I-Application
Request::count1	O
where	O
each	O
instance	O
constructed	O
is	O
assigned	O
a	O
sequential	O
value	O
of	O
count1	O
before	O
it	O
is	O
incremented	O
.	O
</s>
<s>
Since	O
number	O
is	O
an	O
instance	B-Application
variable	I-Application
,	O
each	O
Request	O
object	O
contains	O
its	O
own	O
distinct	O
value	O
;	O
in	O
contrast	O
,	O
there	O
is	O
only	O
one	O
object	O
Request::count1	O
available	O
to	O
all	O
instances	O
with	O
the	O
same	O
value	O
.	O
</s>
