Worldwide, scientists estimate that there are approximately 9,000 to 10,000 species of birds and 22,000 subspecies of birds. Each animal kingdom is split into large groups called phyla. Each phylum is split into smaller groups called classes.
Classes are split into orders of animals. There are 28 orders of birds in the world. Each order is split into families of animals. The world has 82 different families of birds. Different families are split into genera, and genera are split into species, which are finally split into subspecies. As each group is split into smaller groups, such as species and subspecies, the animals within a group become more similar to one another.