Barking is natural communication. Understand different barks' meanings.
Communication
Lack of stimulation causes boredom barking. More exercise/toys help.
Boredom
Anxious, fearful dogs bark at triggers. Desensitize dog to causes.
Fear
Dogs are social. Bark for company. Don't leave alone too long.
Loneliness
Pain, dementia and more lead to barking. Vet check to rule out.
Medical Issue
Dogs learn barking summons you. Ignore demanding barks.
Attention Seeking
Too much freedom causes watch/territorial barking. Limit access.
Boundary Control