Yes, this is a mixed breed cat. They're called Domestic Short Hairs when they have short hair and Domestic Long Hairs when they're long-haired (and sometimes Domestic Medium Hair when they're in the middle). It means the cat is a mutt. In the UK, they're called moggies. All of my cats are this type.
The coat color and coat pattern is called ginger (or orange) tabby and white bicolor.