PDA question

[xpedient]

I am just confused about PDA and GPS. Do all PDAs have GPS or is it an add-on that can be added? If it is an add-on, what units do you recommend that can accomodate the GPS? If not, does GPS only "watch" America or the whole world? Thanks in advance.

 

[LA1]

some PDAs it is built in Some it is an add on like for my Palm pilot.