The 4 D's of dog training are a concept used to help trainers and dog owners remember the four key factors that should be considered when training a dog. The 4 D's are distance, duration, distraction, and difficulty. The distance between you and your dog can affect their ability to understand and respond to your commands. Start training your dog at a close distance and gradually increase the distance over time. The amount of time your dog is expected to perform a behavior can affect their ability to learn and retain the behavior. Start with short training sessions and gradually increase the duration of the training sessions as your dog gets better. Distractions in the environment can make it difficult for your dog to focus on your commands. Start training in a low-distraction environment and gradually increase the level of distraction over time. The level of difficulty of behavior can affect your dog's ability to learn and perform the behavior. Start with easy behaviors and gradually increase the difficulty level as your dog improves.