Is the --target option of the autotool "configure" used for something else than building (cross)compiler?

I've made some cross-compiling in the past and I’ve always wondered what the --target option is used for ?

In what kind of situation do you need to have the --host and --target options different ?

please give some examples.

I've read GNU documenta开发者_Go百科tion but the --target option is still confusing for me.

It's for making a Canadian cross compiler.