Pet sitting is a service in which someone is paid to take care of another person's pet. It often involves things like the pet sitter coming to stay at the home with the pet while the owner is on vacation.
Pet sitting is like babysitting, but for pets. Many owners care a great deal about their pets' well-being and they prefer to have someone come into their home to take care of their pets while they are gone, rather than leave the pets alone or in a kennel. Some pet-sitting services also take place at hotels or resorts, because some people like to bring their pets on vacation with them.