Final answer:
Petechiae are small red or purple dots on the skin caused by blood leaking from damaged vessels, distinct from hives, papules, or wheals.
Step-by-step explanation:
The small red or purple dots that pop up on the skin and are flat are known as Petechiae. These are small red or purple spots that result from blood leaking out of damaged vessels. They are not raised like hives, papules, or wheals, and do not produce pus. Petechiae do not have a soft, pale swelling or redness surrounding them as a result of histamine release, which is characteristic of a wheal from a hypersensitivity reaction.