Fleas and ticks are little parasites that live off your precious dogs blood.
Their biting causes little Bridgett or Spot to feel very uncomfortable and itchy, often leading to dog allergies, and possible Lyme disease
Most often once you've found fleas you can pretty much count on your dog now having tape worm, it comes from the flea and once you've treated the fleas you should have the Vet do a fecal for tape worm.
Depending on the climate you live in, the season for fleas/ticks used to only last 3 or 4 months, However now its different, ticks can be found any time the temperature dips below 0.. Even in December! Things are changing all the time so best to talk to your Vet, they will explain what they are experiencing in your area of the country
Prevention is definitely better than cure, and it's a really good idea to get your puppy started on a regular course of flea and tick preventative as soon as possible. I usually recommend starting tick meds at least a month or two before you think you need them, March or April, where I live here in Ontario, Canada