Phylogeny
A node represents a common ancestor; its descendants form a clade. Shared derived characters can support clades when interpreted relative to an outgroup. Tip order and physical spacing on a page do not establish relatedness. Branch length represents time or amount of change only when a scale or explanation says so. A living species at one tip is not automatically the ancestor of another living tip. Conflicting gene trees can motivate broader sampling rather than certainty from one locus.
In ((A,B),(C,D)), A and B share a more recent common ancestor with each other than either shares with C. Moving B’s label to the other side of its node does not alter that.
Do not count how many centimeters separate the tips. Read the branching pattern, Professor Talon begs you.