What process involves the systematic observation of various areas and entities?

Surveillance refers to the continuous or systematic observation of people, places, or activities to gather detailed information. This process is often utilized to monitor situations over time, ensuring that any changes or developments are recorded and analyzed. In the context of CBRN (Chemical, Biological, Radiological, and Nuclear) reconnaissance operations, surveillance is crucial as it helps in detecting potential threats and gathering intelligence effectively.

In contrast, reconnaissance typically implies an initial exploration or scouting of an area to gather information, often in a more targeted or immediate sense. Inspection usually involves a more thorough examination of specific items or locations rather than continuous observation. Assessment generally refers to the evaluation or analysis of data and information collected but doesn't specifically focus on the ongoing observation process that surveillance entails.