This is a question that we often get from sitter and owners who work with Rover. Help the community out by answering them in our forum!
Shannon L. is correct. Dogs shed. In fact, if you haven't noticed, humans shed too!
Shedding times of the year and shedding amounts depend on the breed of dog, time of year, and health of the dog. Your best bet is to brush regularly to keep the shedding contained and off clothes, furniture, etc. Many people like a dog brush called the "Furminator" easily found at many large and local pet supply stores.
Brushing your dog will help contain the fur and for most dogs is very enjoyable. For pet sitters, be sure and ask the pet owner where they keep their dog's brush and ask if their dog likes brushing. Most of the times dogs love the attention and pet parents like that there is one less thing on their "to do" list and less hair in the house if the pet sitter helps with the brushing!
I've got some bad news for you...
From a general standpoint, dogs shed and you can't stop it. There are breeds of dogs that don't, but if your dog isn't one of them...
Making sure your dog is on a quality food can decrease the amount of shedding. Brushing your dog every day will decrease the amount of fur left behind on floors, rugs, and furniture. There are special tools and shampoos purported to drastically decrease shedding, but they haven't been proven to work as far as I know.
Bottom line: dogs shed.