Final answer:
Unencapsulated sensory receptors, such as free nerve endings, are the most common nerve endings in the skin. They detect painful stimuli, hot and cold temperatures, and light touch.
Step-by-step explanation:
Unencapsulated sensory receptors are a group of sensory receptors that include free nerve endings. These receptors are responsible for detecting painful stimuli, hot and cold temperatures, and light touch. Unencapsulated sensory receptors are the most common nerve endings in the skin and are less sensitive to abrupt changes in stimulation.