python - What does list[x::y] do?

I've
been reading over some sample code lately and I've read quite a few websites but I just
can't seem to get the query right to give me an answer I'm looking for. If anyone could
help me out I'd appreciate it.

class="post-text" itemprop="text">

class="normal">Answer

It
slices

x[startAt:endBefore:skip]

if
you use skip = 2, every other element the list beginning at
startAt and ending at endBefore will
be selected. [Remember: indices live BETWEEN list
elements]

To see this, enter

x =
            range(100)

at the
Python prompt. Then try these
things

x[::2]
x[::3]
x[10:40:6]

and
see what happens.