What is a record ID?

Record ID is a unique number generated by the Zoho Creator system for every record that has been added to the database. Usually it will be a 18 digit number ( eg:272719000003479011 ). 

This number can be displayed in Views. For this,
  1. Click on Edit this application and select the View from the Views tab.
  2. Click on “Column Properties” from the left side view configuration tree.
  3. Locate the column “ID” and put a check mark next to it and click on Done.
  4. You will see this ID when you access the View.
  5. If you still don’t see this, click on More Actions ->Show/hide columns (after accessing the application) and put a check mark to it. 
  6. Click on More Action ->Save Changes for the changes to persist.
What this ID can do? 

Since this is a unique number for every record, it can be used to identify the particular record. This record ID is also useful, when you try to edit/view/PRINT a particular record via URL. 

Deluge field name of this field/column is “ID”.

Can I retain this ID?

Yes, you can do it by converting the ID to a HexaDecimal String. For this, you can create a formula field in the Form and write the formula to retain the ID value as

input.ID.toHex()


Note:
  1. Record ID can be obtained only from the normal database Forms.
  2. Stateless Forms do not store data and they cannot return record IDs from script.