An informant is someone who provides information to authorities, often about illegal activities or wrongdoing. When police investigate a crime, they might rely on an informant who knows what happened and is willing to share what they know. Informants often have inside knowledge because they were present when something occurred or because they're part of a group involved in the activities being investigated.

The word carries a complicated feeling. In detective stories, an informant might help solve a mystery by revealing crucial clues. But informants can also be seen negatively, especially when they're sharing secrets about friends or associates. The word informer means essentially the same thing but often sounds more negative, suggesting betrayal or tattling.

Informant has a different, more neutral meaning in research and journalism. Anthropologists studying a culture rely on informants who teach them about local customs and traditions. Journalists use informants (often called sources) to learn facts for their stories. In these contexts, an informant is simply someone sharing knowledge, without the secretive or negative associations.

The key distinction: informants usually share information that others want to keep hidden, which is why the word often appears in stories about crime, investigation, or research into private or unfamiliar communities.