I've recently discovered that rain is getting in around my exterior (front) door and forming a little pool in the frame under the door. I'm assuming I can fix this by adding a seal around the door (which would also help with insulation too). Is this assumption correct, and if so what products would people recommend for the seal?
EDIT: Sorry, I realise my question was ambiguous, or even completely ill-phrased. The gap in question is actually the gap between the door itself and the door frame within which it's hung. So there has to be some gap there, but it appears that the gap I have is too large or something and that is allowing rain in a bit (when it comes at a particular angle). I'll add some photos once it's light outside ;)