simple question about patches

Hi, i've got a newbie question about patches:
Are the pre* patches ( and i guess also the ac* ones) applied against the
last release of the kernel or against the previous patch? I mean, when
2.4.3pre2 will come out, i need to get also the pre1 patch?

thanks

David Gómez

"The question of whether computers can think is just like the question of
 whether submarines can swim." -- Edsger W. Dijkstra