How does online play work?

PSP support 2 types of multiplayer - adhoc and infrastructure and ad-hoc

most game support ad-hoc, to play multiplayer in games that only support adhoc - you need another psp with same game within 100 feet (not sure)

and infrastructure is traditional online game, check back side of the game box to see what types of online play it supports

You may be mistaking Infastructure with AD-HOC(add hawk).

Most early PSP games such as swbf2 do not have infastructure which is online but do have AD-HOC wich is local (30-50 ft).

The only exception to most early games not having infastructure is probably twisted metal. But the best online games for psp now are SOCOM, KZL, MGS, and Siphon Filter.

hehe, there really don't seem to be any sports fans on this site. :-P yeah, the shooter games have lots of online players, but so do the sports games like Madden, MLB the show, and NBA or NBA live.