<s>
The	O
Apache	B-Application
HTTP	I-Application
Server	I-Application
(	O
)	O
is	O
a	O
free	O
and	O
open-source	B-Application
cross-platform	O
web	B-Application
server	I-Application
software	O
,	O
released	O
under	O
the	O
terms	O
of	O
Apache	B-Application
License	I-Application
2.0	I-Application
.	O
</s>
<s>
Apache	B-Application
is	O
developed	O
and	O
maintained	O
by	O
an	O
open	O
community	O
of	O
developers	O
under	O
the	O
auspices	O
of	O
the	O
Apache	B-Application
Software	O
Foundation	O
.	O
</s>
<s>
The	O
vast	O
majority	O
of	O
Apache	B-Application
HTTP	I-Application
Server	I-Application
instances	O
run	O
on	O
a	O
Linux	B-Application
distribution	I-Application
,	O
but	O
current	O
versions	O
also	O
run	O
on	O
Microsoft	B-Application
Windows	I-Application
,	O
OpenVMS	B-Operating_System
,	O
and	O
a	O
wide	O
variety	O
of	O
Unix-like	B-Operating_System
systems	I-Operating_System
.	O
</s>
<s>
Past	O
versions	O
also	O
ran	O
on	O
NetWare	B-Operating_System
,	O
OS/2	B-Application
and	O
other	O
operating	O
systems	O
,	O
including	O
ports	O
to	O
mainframes	O
.	O
</s>
<s>
Originally	O
based	O
on	O
the	O
NCSA	B-Application
HTTPd	I-Application
server	B-Application
,	O
development	O
of	O
Apache	B-Application
began	O
in	O
early	O
1995	O
after	O
work	O
on	O
the	O
NCSA	O
code	O
stalled	O
.	O
</s>
<s>
Apache	B-Application
played	O
a	O
key	O
role	O
in	O
the	O
initial	O
growth	O
of	O
the	O
World	O
Wide	O
Web	O
,	O
quickly	O
overtaking	O
NCSA	B-Application
HTTPd	I-Application
as	O
the	O
dominant	O
HTTP	B-Application
server	I-Application
.	O
</s>
<s>
In	O
2009	O
,	O
it	O
became	O
the	O
first	O
web	B-Application
server	I-Application
software	O
to	O
serve	O
more	O
than	O
100	O
million	O
websites	O
.	O
</s>
<s>
Cloudflare	O
at	O
19.53	O
%	O
and	O
Microsoft	B-Application
Internet	I-Application
Information	I-Application
Services	I-Application
at	O
5.78	O
%	O
rounded	O
out	O
the	O
top	O
four	O
.	O
</s>
<s>
For	O
some	O
of	O
Netcraft	O
's	O
other	O
stats	O
Nginx	B-Operating_System
is	O
ahead	O
of	O
Apache	B-Application
.	O
</s>
<s>
According	O
to	O
W3Techs	O
review	O
of	O
all	O
web	O
sites	O
in	O
June	O
2022	O
Apache	B-Application
was	O
ranked	O
second	O
at	O
31.4	O
%	O
and	O
Nginx	B-Operating_System
first	O
at	O
33.6	O
%	O
,	O
with	O
Cloudflare	O
Server	B-Application
third	O
at	O
21.6	O
%	O
.	O
</s>
<s>
According	O
to	O
The	O
Apache	B-Application
Software	O
Foundation	O
,	O
its	O
name	O
was	O
chosen	O
"	O
from	O
respect	O
for	O
the	O
various	O
Native	O
American	O
nations	O
collectively	O
referred	O
to	O
as	O
Apache	B-Application
,	O
well-known	O
for	O
their	O
superior	O
skills	O
in	O
warfare	O
strategy	O
and	O
their	O
inexhaustible	O
endurance	O
"	O
.	O
</s>
<s>
This	O
was	O
in	O
a	O
context	O
in	O
which	O
it	O
seemed	O
that	O
the	O
open	O
internet	O
--	O
based	O
on	O
free	O
exchange	O
of	O
open	B-Application
source	I-Application
code	I-Application
--	O
appeared	O
to	O
be	O
soon	O
subjected	O
to	O
a	O
kind	O
of	O
conquer	O
by	O
proprietary	O
software	O
vendor	O
Microsoft	O
;	O
Apache	B-Application
co-creator	O
Brian	O
Behlendorf	O
--	O
originator	O
of	O
the	O
name	O
--	O
saw	O
his	O
effort	O
somewhat	O
parallel	O
that	O
of	O
Geronimo	O
,	O
Chief	O
of	O
the	O
last	O
of	O
the	O
free	O
Apache	B-Application
peoples	O
.	O
</s>
<s>
But	O
it	O
conceded	O
that	O
the	O
name	O
"	O
also	O
makes	O
a	O
cute	O
pun	B-Application
on	O
'	O
a	O
patchy	O
web	O
server'—a	O
server	B-Application
made	O
from	O
a	O
series	O
of	O
patches	O
"	O
.	O
</s>
<s>
There	O
are	O
other	O
sources	O
for	O
the	O
"	O
patchy	O
"	O
software	O
pun	B-Application
theory	O
,	O
including	O
the	O
project	O
's	O
official	O
documentation	O
in	O
1995	O
,	O
which	O
stated	O
:	O
"	O
Apache	B-Application
is	O
a	O
cute	O
name	O
which	O
stuck	O
.	O
</s>
<s>
It	O
was	O
based	O
on	O
some	O
existing	O
code	O
and	O
a	O
series	O
of	O
software	O
patches	O
,	O
a	O
pun	B-Application
on	O
'	O
A	O
PAtCHy	O
 '	O
server.	O
"	O
</s>
<s>
But	O
in	O
an	O
April	O
2000	O
interview	O
,	O
Behlendorf	O
asserted	O
that	O
the	O
origins	O
of	O
Apache	B-Application
were	O
not	O
a	O
pun	B-Application
,	O
stating	O
:	O
</s>
<s>
In	O
January	O
2023	O
,	O
the	O
US-based	O
non-profit	O
Natives	O
in	O
Tech	O
accused	O
the	O
Apache	B-Application
Software	O
Foundation	O
of	O
cultural	O
appropriation	O
and	O
urged	O
them	O
to	O
change	O
the	O
foundation	O
's	O
name	O
,	O
and	O
consequently	O
also	O
the	O
names	O
of	O
the	O
software	O
projects	O
it	O
hosts	O
.	O
</s>
<s>
When	O
Apache	B-Application
is	O
running	O
under	O
Unix	B-Application
,	O
its	O
process	B-Operating_System
name	O
is	O
,	O
which	O
is	O
short	O
for	O
"	O
HTTP	B-Application
daemon	I-Application
"	O
.	O
</s>
<s>
Apache	B-Application
supports	O
a	O
variety	O
of	O
features	O
,	O
many	O
implemented	O
as	O
compiled	B-Language
modules	B-Architecture
which	O
extend	O
the	O
core	O
functionality	O
.	O
</s>
<s>
These	O
can	O
range	O
from	O
authentication	O
schemes	O
to	O
supporting	O
server-side	B-Application
programming	O
languages	O
such	O
as	O
Perl	B-Language
,	O
Python	B-Application
,	O
Tcl	B-Operating_System
and	O
PHP	B-Application
.	O
</s>
<s>
Popular	O
authentication	O
modules	B-Architecture
include	O
mod_access	O
,	O
mod_auth	O
,	O
mod_digest	O
,	O
and	O
mod_auth_digest	O
,	O
the	O
successor	O
to	O
mod_digest	O
.	O
</s>
<s>
A	O
sample	O
of	O
other	O
features	O
include	O
Secure	B-Protocol
Sockets	I-Protocol
Layer	I-Protocol
and	O
Transport	B-Protocol
Layer	I-Protocol
Security	I-Protocol
support	O
(	O
mod_ssl	O
)	O
,	O
a	O
proxy	B-Application
module	B-Architecture
(	O
mod_proxy	O
)	O
,	O
a	O
URL	B-Protocol
rewriting	I-Protocol
module	B-Architecture
(	O
mod_rewrite	O
)	O
,	O
custom	O
log	O
files	O
(	O
mod_log_config	O
)	O
,	O
and	O
filtering	O
support	O
(	O
mod_include	O
and	O
mod_ext_filter	O
)	O
.	O
</s>
<s>
Popular	O
compression	O
methods	O
on	O
Apache	B-Application
include	O
the	O
external	O
extension	O
module	B-Architecture
,	O
mod_gzip	O
,	O
implemented	O
to	O
help	O
with	O
reduction	O
of	O
the	O
size	O
(	O
weight	O
)	O
of	O
web	O
pages	O
served	O
over	O
HTTP	B-Protocol
.	I-Protocol
</s>
<s>
ModSecurity	B-Language
is	O
an	O
open	O
source	O
intrusion	O
detection	O
and	O
prevention	O
engine	O
for	O
Web	O
applications	O
.	O
</s>
<s>
Apache	B-Application
logs	O
can	O
be	O
analyzed	O
through	O
a	O
Web	O
browser	O
using	O
free	O
scripts	O
,	O
such	O
as	O
AWStats/W3Perl	O
or	O
Visitors	O
.	O
</s>
<s>
Virtual	O
hosting	O
allows	O
one	O
Apache	B-Application
installation	O
to	O
serve	O
many	O
different	O
websites	O
.	O
</s>
<s>
For	O
example	O
,	O
one	O
computer	O
with	O
one	O
Apache	B-Application
installation	O
could	O
simultaneously	O
serve	O
example.com,	O
example.org,	O
test47.test-server.example.edu	O
,	O
etc	O
.	O
</s>
<s>
Apache	B-Application
features	O
configurable	O
error	O
messages	O
,	O
DBMS-based	O
authentication	O
databases	B-Application
,	O
content	B-Protocol
negotiation	I-Protocol
and	O
supports	O
several	O
graphical	B-Application
user	I-Application
interfaces	I-Application
(	O
GUIs	B-Application
)	O
.	O
</s>
<s>
Because	O
the	O
source	O
code	O
is	O
freely	O
available	O
,	O
anyone	O
can	O
adapt	O
the	O
server	B-Application
for	O
specific	O
needs	O
,	O
and	O
there	O
is	O
a	O
large	O
public	O
library	O
of	O
Apache	B-Application
add-ons	O
.	O
</s>
<s>
Multiple	O
Request	O
Processing	O
modes	O
(	O
MPMs	O
)	O
including	O
Event-based/Async	B-Application
,	O
Threaded	O
and	O
Prefork	O
.	O
</s>
<s>
TLS/SSL	B-Protocol
with	O
SNI	B-Protocol
and	O
OCSP	B-Protocol
stapling	I-Protocol
support	O
,	O
via	O
OpenSSL	B-Language
or	O
wolfSSL	B-Protocol
.	O
</s>
<s>
Instead	O
of	O
implementing	O
a	O
single	O
architecture	O
,	O
Apache	B-Application
provides	O
a	O
variety	O
of	O
MultiProcessing	O
Modules	B-Architecture
(	O
MPMs	O
)	O
,	O
which	O
allow	O
it	O
to	O
run	O
in	O
either	O
a	O
process-based	O
mode	O
,	O
a	O
hybrid	O
(	O
process	B-Operating_System
and	O
thread	B-Operating_System
)	O
mode	O
,	O
or	O
an	O
event-hybrid	O
mode	O
,	O
in	O
order	O
to	O
better	O
match	O
the	O
demands	O
of	O
each	O
particular	O
infrastructure	O
.	O
</s>
<s>
Where	O
compromises	O
in	O
performance	O
must	O
be	O
made	O
,	O
Apache	B-Application
is	O
designed	O
to	O
reduce	O
latency	O
and	O
increase	O
throughput	O
relative	O
to	O
simply	O
handling	O
more	O
requests	O
,	O
thus	O
ensuring	O
consistent	O
and	O
reliable	O
processing	O
of	O
requests	O
within	O
reasonable	O
time-frames	O
.	O
</s>
<s>
For	O
delivering	O
static	O
pages	O
,	O
Apache	B-Application
2.2	I-Application
series	O
was	O
considered	O
significantly	O
slower	O
than	O
nginx	B-Operating_System
and	O
varnish	B-Language
.	O
</s>
<s>
To	O
address	O
this	O
issue	O
,	O
the	O
Apache	B-Application
developers	O
created	O
the	O
Event	O
MPM	O
,	O
which	O
mixes	O
the	O
use	O
of	O
several	O
processes	O
and	O
several	O
threads	B-Operating_System
per	O
process	B-Operating_System
in	O
an	O
asynchronous	B-Operating_System
event-based	B-General_Concept
loop	I-General_Concept
.	O
</s>
<s>
This	O
architecture	O
as	O
implemented	O
in	O
the	O
Apache	B-Application
2.4	I-Application
series	O
performs	O
at	O
least	O
as	O
well	O
as	O
event-based	O
web	B-Application
servers	I-Application
,	O
according	O
to	O
Jim	O
Jagielski	O
and	O
other	O
independent	O
sources	O
.	O
</s>
<s>
However	O
,	O
some	O
independent	O
but	O
significantly	O
outdated	O
benchmarks	O
show	O
that	O
it	O
is	O
still	O
half	O
as	O
fast	O
as	O
nginx	B-Operating_System
,	O
e.g.	O
</s>
<s>
The	O
Apache	B-Application
HTTP	I-Application
Server	I-Application
codebase	B-General_Concept
was	O
relicensed	O
to	O
the	O
Apache	B-Application
2.0	I-Application
License	I-Application
(	O
from	O
the	O
previous	O
1.1	O
license	O
)	O
in	O
January	O
2004	O
,	O
and	O
Apache	B-Application
HTTP	I-Application
Server	I-Application
1.3.31	O
and	O
2.0.49	O
were	O
the	O
first	O
releases	O
using	O
the	O
new	O
license	O
.	O
</s>
<s>
The	O
OpenBSD	B-Operating_System
project	I-Operating_System
did	O
not	O
like	O
the	O
change	O
and	O
continued	O
the	O
use	O
of	O
pre-2.0	O
Apache	B-Application
versions	O
,	O
effectively	O
forking	B-Application
Apache	B-Application
1.3.x	O
for	O
its	O
purposes	O
.	O
</s>
<s>
They	O
initially	O
replaced	O
it	O
with	O
Nginx	B-Operating_System
,	O
and	O
soon	O
after	O
made	O
their	O
own	O
replacement	O
,	O
OpenBSD	B-Operating_System
Httpd	O
,	O
based	O
on	O
the	O
Relayd	O
project	O
.	O
</s>
<s>
The	O
Apache	B-Application
License	I-Application
1.1	O
was	O
approved	O
by	O
the	O
ASF	O
in	O
2000	O
:	O
The	O
primary	O
change	O
from	O
the	O
1.0	O
license	O
is	O
in	O
the	O
'	O
advertising	O
clause	O
 '	O
(	O
section	O
3	O
of	O
the	O
1.0	O
license	O
)	O
;	O
derived	O
products	O
are	O
no	O
longer	O
required	O
to	O
include	O
attribution	O
in	O
their	O
advertising	O
materials	O
,	O
only	O
in	O
their	O
documentation	O
.	O
</s>
<s>
The	O
ASF	O
adopted	O
the	O
Apache	B-Application
License	I-Application
2.0	I-Application
in	O
January	O
2004	O
.	O
</s>
<s>
The	O
Apache	B-Application
HTTP	I-Application
Server	I-Application
Project	O
is	O
a	O
collaborative	O
software	O
development	O
effort	O
aimed	O
at	O
creating	O
a	O
robust	O
,	O
commercial-grade	O
,	O
feature-rich	O
and	O
freely	O
available	O
source	O
code	O
implementation	O
of	O
an	O
HTTP	B-Protocol
(	O
Web	O
)	O
server	B-Application
.	O
</s>
<s>
The	O
project	O
is	O
jointly	O
managed	O
by	O
a	O
group	O
of	O
volunteers	O
located	O
around	O
the	O
world	O
,	O
using	O
the	O
Internet	O
and	O
the	O
Web	O
to	O
communicate	O
,	O
plan	O
,	O
and	O
develop	O
the	O
server	B-Application
and	O
its	O
related	O
documentation	O
.	O
</s>
<s>
This	O
project	O
is	O
part	O
of	O
the	O
Apache	B-Application
Software	O
Foundation	O
.	O
</s>
<s>
Apache	B-Application
2.4	I-Application
dropped	O
support	O
for	O
BeOS	B-Application
,	O
TPF	B-Operating_System
,	O
A/UX	B-Operating_System
,	O
NeXT	O
,	O
and	O
Tandem	O
platforms	O
.	O
</s>
<s>
Apache	B-Application
,	O
like	O
other	O
server	B-Application
software	I-Application
,	O
can	O
be	O
hacked	O
and	O
exploited	O
.	O
</s>
<s>
The	O
main	O
Apache	B-Application
attack	O
tool	O
is	O
Slowloris	O
,	O
which	O
exploits	O
a	O
bug	O
in	O
Apache	B-Application
software	O
.	O
</s>
<s>
It	O
creates	O
many	O
sockets	O
and	O
keeps	O
each	O
of	O
them	O
alive	O
and	O
busy	O
by	O
sending	O
several	O
bytes	O
(	O
known	O
as	O
"	O
keep-alive	O
headers	O
"	O
)	O
to	O
let	O
the	O
server	B-Application
know	O
that	O
the	O
computer	O
is	O
still	O
connected	O
and	O
not	O
experiencing	O
network	O
problems	O
.	O
</s>
<s>
The	O
Apache	B-Application
developers	O
have	O
addressed	O
Slowloris	O
with	O
several	O
modules	B-Architecture
to	O
limit	O
the	O
damage	O
caused	O
;	O
the	O
Apache	B-Application
modules	I-Application
mod_limitipconn	O
,	O
mod_qos	O
,	O
mod_evasive	O
,	O
mod	B-Language
security	I-Language
,	O
mod_noloris	O
,	O
and	O
mod_antiloris	O
have	O
all	O
been	O
suggested	O
as	O
means	O
of	O
reducing	O
the	O
likelihood	O
of	O
a	O
successful	O
Slowloris	O
attack	O
.	O
</s>
<s>
Since	O
Apache	B-Application
2.2.15	O
,	O
Apache	B-Application
ships	O
the	O
module	B-Architecture
mod_reqtimeout	O
as	O
the	O
official	O
solution	O
supported	O
by	O
the	O
developers	O
.	O
</s>
