<s>
Data	B-General_Concept
extraction	I-General_Concept
is	O
the	O
act	O
or	O
process	O
of	O
retrieving	O
data	O
out	O
of	O
(	O
usually	O
unstructured	B-Application
or	O
poorly	O
structured	O
)	O
data	O
sources	O
for	O
further	O
data	B-General_Concept
processing	I-General_Concept
or	O
data	B-General_Concept
storage	I-General_Concept
(	O
data	B-General_Concept
migration	I-General_Concept
)	O
.	O
</s>
<s>
The	O
import	B-General_Concept
into	O
the	O
intermediate	O
extracting	O
system	O
is	O
thus	O
usually	O
followed	O
by	O
data	B-General_Concept
transformation	I-General_Concept
and	O
possibly	O
the	O
addition	O
of	O
metadata	O
prior	O
to	O
export	B-General_Concept
to	O
another	O
stage	O
in	O
the	O
data	O
workflow	B-Operating_System
.	O
</s>
<s>
Usually	O
,	O
the	O
term	O
data	B-General_Concept
extraction	I-General_Concept
is	O
applied	O
when	O
(	O
experimental	O
)	O
data	O
is	O
first	O
imported	O
into	O
a	O
computer	O
from	O
primary	O
sources	O
,	O
like	O
measuring	O
or	O
recording	O
devices	O
.	O
</s>
<s>
Today	O
's	O
electronic	O
devices	O
will	O
usually	O
present	O
an	O
electrical	B-Protocol
connector	I-Protocol
(	O
e.g.	O
</s>
<s>
USB	B-Protocol
)	O
through	O
which	O
'	O
raw	O
data	O
 '	O
can	O
be	O
streamed	B-General_Concept
into	O
a	O
personal	B-Device
computer	I-Device
.	O
</s>
<s>
Typical	O
unstructured	B-Application
data	I-Application
sources	O
include	O
web	O
pages	O
,	O
emails	O
,	O
documents	O
,	O
PDFs	B-Application
,	O
scanned	O
text	O
,	O
mainframe	O
reports	O
,	O
spool	O
files	O
,	O
classifieds	O
,	O
etc	O
.	O
</s>
<s>
Extracting	O
data	O
from	O
these	O
unstructured	B-Application
sources	O
has	O
grown	O
into	O
a	O
considerable	O
technical	O
challenge	O
where	O
as	O
historically	O
data	B-General_Concept
extraction	I-General_Concept
has	O
had	O
to	O
deal	O
with	O
changes	O
in	O
physical	O
hardware	O
formats	O
,	O
the	O
majority	O
of	O
current	O
data	B-General_Concept
extraction	I-General_Concept
deals	O
with	O
extracting	O
data	O
from	O
these	O
unstructured	B-Application
data	I-Application
sources	O
,	O
and	O
from	O
different	O
software	O
formats	O
.	O
</s>
<s>
This	O
growing	O
process	O
of	O
data	B-General_Concept
extraction	I-General_Concept
from	O
the	O
web	O
is	O
referred	O
to	O
as	O
"	O
Web	O
data	B-General_Concept
extraction	I-General_Concept
"	O
or	O
"	O
Web	B-Application
scraping	I-Application
"	O
.	O
</s>
<s>
Using	O
text	O
pattern	B-Language
matching	I-Language
such	O
as	O
regular	B-Language
expressions	I-Language
to	O
identify	O
small	O
or	O
large-scale	O
structure	O
e.g.	O
</s>
