1. A probe (or scan) of a network or computer is when another computer sends a variety of different messages to the network or computer with the goal of getting particular responses. These responses can then be used to infer information about the targeted system. While there are many benign uses for network scans (either for research, or for more effective system administration), they are also considered to be potential precursors to more serious attacks because they can give the attacker information about a network’s weak points.
Source: Election Cybersecurity 101 Field Guide – Glossary, Center for Democracy & Technology, https://cdt.org/insight/election-cybersecurity-101-field-guide-glossary/
2. In information operations, any attempt to gather information about an automated information system or its online users. (JP 1-02 & JP 3-13).
Source: Terms & Definitions of Interest for DoD Counterintelligence Professionals, Office of the National Counterintelligence, https://www.dni.gov/files/NCSC/documents/ci/CI_Glossary.pdf