A police notebook, pocket notebook or PNB is a notebook used by police officers to officially record details and incidents while on patrol. Its use is controlled by a number of guidelines, as information entered into an officer's PNB is admissible in court, and the officer will use it to refresh his memory while giving evidence, and to support his statements.

While the guidelines for maintaining a PNB will differ from force to force, there are several common policies on using the notebooks. In the United Kingdom the use of the PNBs is dictated by the 2000 Freedom of Information Act. All PNBs are subject to the same rules of disclosure as other confidential documents, and must contain everything deemed relevant to police work. Each new entry is marked with the day and date in capital letters, and is ended with a line covering the entire width of the page, along with the officers signature. No information may be removed, and all corrections must be made by striking the incorrect entry with a line and the correct entry should be inserted with the officer's initials. Time is required to be written in 24 hour style, and any gaps left at the end of a line must be filled by a horizontal line to show that the gap was not created by the removal of a word. Many forces also require directly quoted speech to be written in capitals.

When an officer needs to record information in his notebook the following are required by several forces:

- Time of day
- Exact or approximate location
- Offense or occurrence
- Names and addresses of offenders, victims or witnesses
- Action taken by the officer involved (eg. arrests).
- Some forces require the officer to write down what he or she said during the incident.