What does Day and Immediate validity mean?

These terms define how long your order stays active in the market before it is executed or cancelled.
Day Validity: The order remains active for the full trading day and is automatically cancelled if it is not executed by market close.
IOC (Immediate or Cancel) Validity: The order is executed immediately, either fully or partially, at the available price. Any unexecuted portion is cancelled instantly and does not remain pending.