[prawn]

Last time I undertook a major trip (37 flights through 20ish countries), there were two main alliances - Star and OneWorld, from memory. If you stuck to airlines from one of those, your points would be combined.

I don't fly all that regularly (maybe just above average) so things might've changed since then.

[gaius]

Now there is a third - SkyTeam. Plus there is Virgin Atlantic who aren't a member of any alliance but have one-off deals with individual airlines.