Diary studies ask participants to record relevant activities and experiences over days or weeks in their everyday context. Use them to investigate recurring behaviour, changing attitudes or journeys that a single research session would miss. Define the research question, participants, reporting period and prompts; choose event-triggered entries, regular intervals or researcher reminders. Pilot the instructions and collection tools, monitor submissions and clarify gaps while events are fresh. Finish with follow-up interviews and analyse patterns across time, remembering that the entries are self-reported.