text: What is the sixth category.  Life is put into five categories, monera, fungi, protists, plants and animals.  There are two ways of determining which beings go in which category.  The older way is called the phenetic way, in which animals are categorized based on common traits.  For instance, all mammals have fur.  The more common way of classifying animals is the cladistic way, which groups organisms based on common evolutionary backgrounds.  All mammals at one point in development have gill slits, a notochord, etc.