Dogs bark  for a number of reasons ,but the motivation  is to get attention from their people , either to get something  they want such as pats or a game ,   , or to get help from  them to ward off a perceived threat  such as a  passerby or another dog barking in the distance . ( A dog who doesn’t bark at you is far more likely to bite,   because it doesn’t feel a  need for  back up ).

People who respond to  their  dog’s  barking  for attention or a game  inadvertently  teach their  dogs to bark when they want something, and if you don’t respond they will persist  until you  do .Most people are simply not capable of ignoring it  until the  dog gives up . 

If you yell at your dog for  barking at a trigger  of some sort(  eg passerby , birds , another  dog barking , or  the doorbell ),  your dog will either not understand  and will think you are barking at what it’ s barking at , which is what it wanted , or  will become fearful of you . The barking wont stop !

If your  dog is barking for attention or at a trigger of any sort , this  is easily resolved  by changing how your  dog feels about the trigger , or providing or teaching a  better alternative  or a different ,  unrewarding (but not painful or scary ) consequence .