Journal fields technically don't store data in the table that the Journal field is on, but instead, create entries in the Journal Entries [sys_journal_field] table. These journal entries, along with other values corresponding to changes to audited fields from the Sys Audits [sys_audit], History [sys_history_line], and Record History [sys_history_set] tables, are displayed in the Activity formatter.
Note
Journal fields only work on audited tables. Adding such a field will modify a non-audited table's System Dictionary entry so that it becomes audited.
There are three types of Journal fields that you can add to your forms: journal_list, journal, and journal_input.
journal_list fields don't actually store data, but are used more like formatters. Formatters are a way of displaying data or other content (other than regular form fields) in ServiceNow forms. If you visit the dictionary record for a journal_list field (such as when you're creating it), you can...