The Record ID is the internal reference number (integer) used by the system to identify a Record within a Table.
The Record ID is stored regardless of whether a field of type Record ID is added to the Table: adding such a field simply exposes the value for use in Queries etc.
Record IDs are generally issued sequentially, however this should not be assumed, so if you need to sort in order of record creation, use the Created datatype
If a record is deleted, the Record ID of the deleted record will not be reused by new records.
Read-only - the value in the field cannot be changed.