I degree burns are also called erythematous burns. The local area is dry, painful, slightly swollen and red, without blisters. 3-5 d later, the local area turns from red to light brown, the epidermis wrinkles and peels off, revealing a red and smooth epithelial surface and healing. Second degree burns 1, shallow II degree burns: local redness and swelling is obvious, there are blisters of varying sizes formed, containing a light yellow (sometimes light red) clarified liquid or gelatinous material containing protein coagulation. After the blister is cut and lifted, a red and moist trabecular surface is visible with a soft texture, pain sensitivity, and a myriad of dilated, congested capillary networks that appear granular or pulsatile, more pronounced 1 to 2 d after the injury. In the normal skin structure, there is a vascular network at the junction of the papillary layer and the reticular layer, called the superficial cutaneous vascular network, and branches emanate from it to reach into each papilla. In superficial second-degree burns, they are dilated and congested, so the clinical presentation is granular or pulsatile vascular network. When superficial degree II burns affect the papillary layer, the vascular network is mostly pulsatile and less granular. 2, deep II degree burns: local swelling, epidermis is whiter or brownish-yellow, intermittently there are smaller blisters. After removing the necrotic epidermis, the trauma surface is slightly wet, slightly red or white in red, red-white, tougher, dull sensation, lower temperature, and visible red dots the size of corn, or tiny dendritic vessels, more obvious 1-2 d after the injury. This is because the shallow skin vascular network has been coagulated, the red dots seen for sweat glands, hair follicles around the capillary expansion of congestion. Therefore, the more superficial the burn, the more obvious the red dots are; the deeper they are, the more blurred they are. The few tiny vessels are dilated and congested or embolized deep skin vascular networks located in the reticular layer and at the junction of the reticular layer and subcutaneous fat. Their presence often indicates deeper second-degree burns. Third-degree burns Third-degree burns are also known as scorch burns. The area is pale, blister-free, insensitive and cold. The texture is tough and leathery. A thick network of blood vessels is often visible through the scab, which is very different from the fine and dense small vessels of the deep II degree. This is due to venous congestion or embolization and coagulation in the subcutaneous fat layer, and is more common in the thinner skin of the inner extremities. Most of them can appear after the injury, sometimes 1-2d or longer after the injury, especially for the third degree burns caused by scalding, which need to wait until the scabs are slightly dry before they appear. The hairs of the scab are easy to remove, and there is no pain when they are removed. If it is a third-degree burn caused by boiling water, there are sometimes tiny blisters under the necrotic epidermis, and when the blister skin is torn off, the base is white and tougher. Fourth-degree burns, yellowish brown or charred or dried, loss of consciousness, limited movement, amputation (fingers) or flap repair is required.