Why does my dog bark at strangers?

thats what they do unless they are trained

My dog does that to. he only barks when it's someone he isn't used to. Actually, this was helpful for us. we have a smaller dog (not tiny,) he's.... insane. seriously. Well, robbers had been going around our neiborhood and breaking into cars. cuz of my dog, we were the ONLY ones that were left alone. If you don't want your dog to bark, let him know you don't want him doing that. spray bottles, telling him know, something. It CAN be REALLY, REALLY annoying, so I can understand why you don't want him barking.

Because dogs think of youk as their territory when a stranger approaches them they are instantly alert and try to defend their territory

this is a bad thing? hes letting you know theres someone new around. unless he becomes overly agressive towards the person without good cause. than consider yourself lucky you've got a real live alarm system.

Because thats what Dogs do.

Cause your dog wants to keep you safe from strangers. :)

They scare him.