When you collect data with Magpi there are several automatically-generated data fields, as shown in this screenshot from Data tab of the Magpi website:

They are defined as follows:

Created by  the identification (username or email or phone) for the user who first created the record.  This never changes after the data record is created.

Last Modifier - the identification for whoever made the last edit to the record (for example, a data manager cleaning the data on the Magpi website). Initially it is the same as Created By, but will change with subsequent edits if the editor is different from the Created By user.

Start recordwhen the form was opened (i.e. when the data record was first created).  This datestamp never changes after it is first recorded.

End recordwhen the form was first saved. This datestamp never changes after it is first recorded.

Last submit when the data record was either (1) first added to the Magpi web server [usually by uploading data from a mobile device to the Magpi server], or (2) subsequently edited, either on a mobile device or on the website.