When people and dogs first met thousands of years ago, the dogs were wild and sort of like wolves. Over time, people started to notice that some of these dogs were good at helping them hunt or protect their homes. People would give these helpful dogs food and shelter in return for their help.
Eventually, these dogs started to change. They got used to living with people and started to depend on them for food and protection. They also started to enjoy being around people and learned to wag their tails and do tricks to make people happy.
The dogs that were the friendliest and most helpful to people were chosen to breed and have puppies. This made the puppies even friendlier and more helpful than before. Over a long time, people kept choosing the nicest and most helpful dogs to breed, and this is how we got all the different types of dogs we have today.
So basically, domestication of dogs means that people took wild dogs and turned them into the friendly, helpful pets we know and love today!