To learn more https://www.khanacademy.org/science/biology/her/tree-of-life/a/building-an-evolutionary-tree

When we are building phylogenetic trees, traits that arise during the evolution of a group and differ from the traits of the ancestor of the group are called derived traits. In our example, a fuzzy tail, big ears, and whiskers are derived traits, while a skinny tail, small ears, and lack of whiskers are ancestral traits.

To learn more https://www.ck12.org/book/ck-12-human-biology/section/2.5/

To learn more https://www.thoughtco.com/three-domain-system-373413