Spare parts can be many different objects, and belong to many different things. You can talk about spare parts for all motorized vehicles, such as cars, tractors, motorcycles, etc., but you can also talk about it in relation to electronics, such as computers and cameras, as well as various other machines. Some spare parts can be really rare. It may be that you have a car from the 60s, and something about it needs to be replaced, but since you want the original parts, it can be difficult. Fortunately, there are some who do not deal with anything other than looking for special spare parts, and these can even replace them.