A
millennium
is
a
period
of
one
thousand
consecutive
years.
When
dating
years,
millennia
are
usually
taken
to
begin
in
the
years
divisible
by
one
thousand,
or
alternatively
in
the
year
after
that,
e.g.,
2000
or
2001.
The
use
of
the
odd
year
came
from
the
Anno
Domini
system
of
religious
dating,
where
the
year
1
was
supposedly
the
first
"year
of
our
lord"
and
thus
the
first
millennium
would
be
years
1
to
1000
and
the
second
millennium
would
start
in
1001.
There was a popular
debate leading up to the celebrations of the year 2000
as to whether 2000
was the true "new millennium". Some argued that based on the Anno
Domini system, the "true" new millennium would begin in 2001.
Others argued that under the Gregorian
Calendar centuries should be observed at the first numerical
departure from the previous millennium (ie: we are in a new millennium
when we stop being in the 1900s). Others argued that our entire
system of dates is so arbitrary and meaningless that it is impossible
to define the "true" date of a millennium.