The History field is a special embedded table data type, automatically generated for new tables, which creates date/user stamped history records of all edits and events that occurred in a record, in order to maintain a history of everything that happens in the system. This is a critical resource for storing data that is used by reports and rules and should never be deleted. In addition, history provides a full audit trail of all changes made to a record with snapshot capability that shows what a record looked like after any set of changes.
Since the history field is included and added to the table wizard and record layout by default, you cannot directly add a history field.
If a record change was triggered by a rule due to another record's modification, the The History displays the table and record IDs which triggered the record change as clickable links.
In new tables, all fields are selected by default. You should remove fields from history only if you are clear about the reasons and consequences, such as an effect on system performance.
If you remove a field from history tracking, when you view a history snapshot by clicking View [Record] After Change, that field's value will show as "Not tracked" or, if it is a multiple linked field, "No records."
To change how fields are tracked in history...
Whenever a new field is added to a table, it will also be automatically added to the History record table. Due to the potential size of History tables, this can cause major database load issues since the field has to be added to every history record for the table. De-selecting the Auto-add new fields to History checkbox allows you to schedule the History update and minimize database workload.
On the Field Permissions tab of the Table Permissions wizard, you can enable users to modify the History field. This permission should only be granted to admin-level users, and used carefully. For instance, timed rules can be set up to delete previous history records, so the history of the record doesn't weigh down the updates for timed rules. In general, this permission is only used during the implementation phase of a system to clear out history when needed.