Learn in the textbookThe Preparation Stage of an Attack — Reconnaissance
DefinitionFootprinting (フットプリンティング) is researching a target organization before an attack by gathering publicly available information about it.
ExplanationFor example, an attacker may pick up employee names, the format of email addresses, and hints about the products in use from the organization's website, social media posts, and job ads. The information can then be used to narrow down which people or devices to aim at, and to prepare for later technical probing or attacks that trick people.
AnalogyIt is like checking reviews, a map, and the notices posted outside a shop on a trip before going in, so you have a rough idea of its hours and how crowded it gets. You stay outside and size it up using only what can be seen from there.
Memory hookA footprint is a trace left behind: footprinting collects the traces a target has left out in the world.