Someone who would like to talk to a journalist to provide information without being identified can ask to speak to the journalist "off the record." If the journalist agrees that the source is off the record, the journalist would use the information without naming the source. This is common where the source would face consequences for being quoted -- e.g., the source wants to give information about their employer without getting fired. This is an agreement between the source and the journalist, which means that the journalist must agree to anonymity up front and the source cannot insist on it afterward (e.g. because they realize they said something that can get them in trouble). Journalists generally follow these agreements because it would be harmful to their reputation and ability to get sources in the future if they were known to burn their sources, but there's likely no other recourse for a source that believe that they were "off the record" and where then cited by the journalist.

There are various types of "off the record" that are understood to exist, and people, especially in politics or national security would generally be familiar with them. The most common are "background" and "deep background," with "background" indicating that the source could only be cited with consent (i.e. the journalist can't say "My sources in the White House tell me..." unless the source agrees) and "deep background" meaning that the journalist can use the information but they can't even anonymously cite the source (i.e. no "My anonymous source at the Pentagon tells me...").