How to find out that a record has been updated

Hi all

I have an application that reads the contents of a few tables every 2 hours.

If no new records have been added, and if no updates to existing records
have been made in the last 2 hours, the app does nothing.

If some records have been updated or added, the app does some work, and
marks the record as processed.

Currently anyone updating a record is expected to mark it manually as
needing processing. Otherwise the application doesn't know.

Is there a better, more user friendly way, for the app to automatically find
out which records have been updated. Maybe a column that has a time field
that Postgres can update to "now" each time an update is made?

Thanks

PVS

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