To those of us who from childhood have shared hearth and home with a variety of pets it is hard to imagine any other way of life, but in fact there are many people who reach maturity without having any real contact with an animal of any kind. Animals make extra work, cost money and are an ongoing responsibility for 365 days a year. They are not for everyone. Pets such as dogs and cats bring in mud and leave hairs on the carpets and furniture. Young animals need housetraining, while birds spill their seed all over the place.
Young dogs are often destructive, they chew things and dig holes in the garden.
People who are used to animals take such things in their stride, but we are not all cast in the same mould and sometimes a family finds itself in considerable strife over such issues. If so, you may need to postpone obtaining a dog or cat until you own your own home. Some landlords will allow a dog and many more will allow a cat, but the problem may come when you have to move and the next landlord has a 'No Pets' clause in his agreement. A pet is not a disposable item, it is a member of your family, so bear this in mind if you are renting a home. A pet ties you down.