<s>
A	O
portable	B-Device
storage	I-Device
device	I-Device
(	O
PSD	O
)	O
is	O
a	O
compact	O
plug-and-play	B-Device
mass	B-Device
storage	I-Device
device	I-Device
designed	O
to	O
hold	O
a	O
large	O
volume	B-Application
of	O
digital	B-General_Concept
data	I-General_Concept
of	O
any	O
kind	O
.	O
</s>
<s>
This	O
is	O
slightly	O
different	O
from	O
a	O
portable	O
media	O
player	O
,	O
which	O
is	O
designed	O
to	O
only	O
store	O
music	O
and	O
video	B-General_Concept
files	I-General_Concept
that	O
its	O
internal	O
reader	O
softwares	O
can	O
play	O
.	O
</s>
<s>
Most	O
modern	O
PSDs	O
are	O
dedicated	O
solid	B-Device
state	I-Device
drives	I-Device
(	O
SSD	B-Device
)	O
that	O
are	O
connected	O
to	O
a	O
computer	O
and	O
powered	O
via	O
USB	B-Protocol
ports	I-Protocol
.	O
</s>
<s>
Some	O
PSDs	O
,	O
usually	O
those	O
from	O
before	O
the	O
wide	O
adoption	O
of	O
SSDs	B-Device
,	O
are	O
modified	O
hard	B-Device
disk	I-Device
drives	I-Device
via	O
the	O
installation	O
of	O
a	O
disk	B-Device
enclosure	I-Device
,	O
and	O
require	O
an	O
additional	O
AC	O
adapter	O
as	O
the	O
power	O
required	O
to	O
operate	O
the	O
drive	O
typically	O
exceeds	O
that	O
can	O
be	O
provided	O
by	O
the	O
USB	B-Protocol
port	I-Protocol
.	O
</s>
<s>
PSDs	O
,	O
while	O
much	O
bigger	O
and	O
heavier	O
than	O
ultracompact	O
flash	B-Device
drives	I-Device
such	O
as	O
USB	B-Protocol
flash	B-Device
drives	I-Device
and	O
memory	B-Device
cards	I-Device
,	O
offer	O
significantly	O
more	O
external	B-Device
storage	I-Device
capacities	O
,	O
yet	O
are	O
still	O
convenient	O
enough	O
for	O
carrying	O
around	O
when	O
travelling	O
or	O
as	O
a	O
readily	O
accessible	O
offline	O
backup	B-Protocol
storage	I-Protocol
option	O
,	O
especially	O
in	O
situations	O
where	O
online	O
storage	O
alternatives	O
such	O
as	O
network-attached	B-Application
storage	I-Application
and	O
cloud	O
storage	O
are	O
unavailable	O
,	O
unreliable	O
or	O
unsafe	O
.	O
</s>
<s>
One	O
type	O
of	O
data	O
that	O
may	O
be	O
stored	O
is	O
digital	O
photographs	O
(	O
RAW	B-Application
data	O
)	O
,	O
transferred	O
from	O
a	O
digital	B-Device
camera	I-Device
.	O
</s>
<s>
Many	O
PSDs	O
will	O
connect	O
directly	O
to	O
a	O
camera	O
and	O
copy	O
the	O
images	O
,	O
or	O
they	O
may	O
provide	O
a	O
slot	O
for	O
a	O
memory	B-Device
card	I-Device
to	O
plug	O
in	O
,	O
with	O
or	O
without	O
a	O
card	B-Device
reader	I-Device
device	O
.	O
</s>
