<s>
In	O
version	B-Architecture
control	I-Architecture
software	I-Architecture
,	O
a	O
changeset	B-Protocol
(	O
also	O
known	O
as	O
commit	O
and	O
revision	O
)	O
is	O
a	O
set	O
of	O
alterations	O
packaged	O
together	O
,	O
along	O
with	O
meta-information	O
about	O
the	O
alterations	O
.	O
</s>
<s>
A	O
changeset	B-Protocol
describes	O
the	O
exact	O
differences	O
between	O
two	O
successive	O
versions	O
in	O
the	O
version	B-Architecture
control	I-Architecture
system	I-Architecture
's	O
repository	O
of	O
changes	O
.	O
</s>
<s>
Changesets	B-Protocol
are	O
typically	O
treated	O
as	O
an	O
atomic	B-General_Concept
unit	O
,	O
an	O
indivisible	O
set	O
,	O
by	O
version	B-Architecture
control	I-Architecture
systems	I-Architecture
.	O
</s>
<s>
This	O
is	O
one	O
synchronization	B-General_Concept
model	I-General_Concept
.	O
</s>
<s>
In	O
the	O
Git	B-Application
version	I-Application
control	I-Application
system	I-Application
a	O
changeset	B-Protocol
is	O
called	O
a	O
commit	O
,	O
</s>
<s>
not	O
to	O
be	O
confused	O
with	O
the	O
commit	B-Protocol
operation	I-Protocol
that	O
is	O
used	O
to	O
commit	O
a	O
changeset	B-Protocol
(	O
or	O
in	O
Git	B-Application
's	O
case	O
technically	O
a	O
snapshot	B-Application
)	O
to	O
a	O
repository	O
.	O
</s>
<s>
Other	O
version	B-Architecture
control	I-Architecture
systems	I-Architecture
also	O
use	O
other	O
names	O
to	O
refer	O
to	O
changesets	B-Protocol
,	O
for	O
example	O
Darcs	B-Protocol
calls	O
them	O
"	O
patches	O
"	O
,	O
</s>
<s>
Version	B-Architecture
control	I-Architecture
systems	I-Architecture
attach	O
metadata	O
to	O
changesets	B-Protocol
.	O
</s>
<s>
Typical	O
metadata	O
includes	O
a	O
description	O
provided	O
by	O
the	O
programmer	O
(	O
a	O
"	O
commit	O
message	O
"	O
in	O
Git	B-Application
lingo	O
)	O
,	O
the	O
name	O
of	O
the	O
author	O
,	O
the	O
date	O
of	O
the	O
commit	O
,	O
etc	O
.	O
</s>
<s>
Unique	O
identifiers	O
are	O
an	O
important	O
part	O
of	O
the	O
metadata	O
which	O
version	B-Architecture
control	I-Architecture
systems	I-Architecture
attach	O
to	O
changesets	B-Protocol
.	O
</s>
<s>
Centralized	O
version	B-Architecture
control	I-Architecture
systems	I-Architecture
,	O
such	O
as	O
Subversion	B-Application
and	O
CVS	B-Application
simply	O
use	O
incrementing	O
numbers	O
as	O
identifiers	O
.	O
</s>
<s>
Distributed	B-Protocol
version	I-Protocol
control	I-Protocol
systems	I-Protocol
,	O
such	O
as	O
Git	B-Application
,	O
generate	O
a	O
unique	O
identifier	O
by	O
applying	O
a	O
cryptographic	B-Algorithm
hash	I-Algorithm
function	I-Algorithm
to	O
the	O
changeset	B-Protocol
.	O
</s>
<s>
Because	O
version	B-Architecture
control	I-Architecture
systems	I-Architecture
operate	O
on	O
changesets	B-Protocol
as	O
atomic	B-General_Concept
units	O
,	O
and	O
because	O
communication	O
within	O
development	O
teams	O
improves	O
performance	O
,	O
there	O
are	O
certain	O
best	O
practices	O
to	O
follow	O
when	O
creating	O
changesets	B-Protocol
.	O
</s>
<s>
Only	O
the	O
2	O
most	O
significant	O
are	O
mentioned	O
here	O
,	O
changeset	B-Protocol
content	O
atomicity	B-General_Concept
and	O
changeset	B-Protocol
descriptions	O
.	O
</s>
<s>
Changeset	B-Protocol
content	O
should	O
involve	O
only	O
one	O
task	O
or	O
fix	O
,	O
and	O
contain	O
only	O
code	O
which	O
works	O
and	O
does	O
not	O
knowingly	O
break	O
existing	O
functionality	O
.	O
</s>
<s>
Changeset	B-Protocol
descriptions	O
should	O
be	O
short	O
,	O
recording	O
why	O
the	O
modification	O
was	O
made	O
,	O
the	O
modification	O
's	O
effect	O
or	O
purpose	O
,	O
and	O
describing	O
non-obvious	O
aspects	O
of	O
how	O
the	O
change	O
works	O
.	O
</s>
