I never heard of that term before. Been trading for a few years now and I never heard of backfill. What is it? Is it propieratory to IB? None of the brokers I ever used never mentioned it. It's not in their software. What is it?
Historical intraday data and charts, can be used with the charting program in TWS or from third parties.
So it's not really a fill? IB's backfill is just another name for historical charts? The same historical charts that other charting services provide? But other charting software providers just call it 'historical' charts. Why does IB name their historical charts 'backfill'? Just to be different? Confusing. But ok....lol.
To be more precise, some charting packages only display the data that they acquire while they are running, so if you were to, say, run the application only at around midday then you won't be able to see a chart for the first 2.5 hours (assume we are talking about stocks and New York time). Backfill feature essentially backfills that data so when you run your application you can see the full days trading not just the time you were logged on.
Now I see why they call it backfill. That makes sense. Thank you everybody for explaining what backfills are.