I've been reading on the forum about excessive barking, and how to prevent it.
My pup is 13 weeks old and does not bark excessively, but only gives the occasional "shout" when we are playing - should I correct this, or allow him to let off a little bit of steam in this way when he is having fun? I don't want to stop him expressing his enjoyment, but I don't want him to start getting over excited. I never respond to him if he barks for attention, which isn't very often anyway - but wait until he is quiet. It just seems such a shame to stop a game if he barks once or twice, especially when his tailing is wagging like crazy. Any ideas would be very welcome, please.

I would never stop a dog barking entirely - I mean, I want to be alerted to intruders/danger etc! And, just like children out of class at breaktime, pups and adults need to vocalise during play. You just need to prevent excessive barking.
Hope this helps.
:)

Depends what you mean by "excessive" dosen't it? If he's playing that's 1 thing, you've already taught him not to demand attention by barking and they shouldn't bark when yu talk to someone else or answer the door, but barking because someone he dosen't know comes in the house could be useful. If he barked at night I'd go check.