Final answer:
Pressure ulcers are classified into four stages, with stage 1 characterized by non-blanchable erythema and intact skin.
Step-by-step explanation:
Pressure ulcers, also known as bedsores or decubitus ulcers, are classified into four stages based on the extent of tissue damage. Stage 1 pressure ulcers are characterized by non-blanchable erythema, which means that the affected area appears red and does not turn white when pressed. The skin remains intact in stage 1 and there may be some warmth or pain in the area.