What is the primary role of a "sentinel"?

The primary role of a "sentinel" is to guard and watch over, which emphasizes the function of a sentinel as a protector or lookout. Traditionally, the term has been used to describe sentries or watchmen who monitor and observe for potential threats or dangers, ensuring safety and security. This role is critical in many contexts, such as military operations, wildlife conservation, and even in metaphorical uses where vigilance is required. The essence of being a sentinel lies in the act of observation and safeguarding, highlighting the importance of being alert and ready to respond to any situation that may arise.