Short answer

Longterm (CNC), Intraday (MIS), and Overnight (NRML) are product types used when placing orders through Arrow.

Longterm (CNC - Cash and Carry)

Longterm (CNC) is used for delivery-based trading in equity. This product type allows you to hold stocks overnight for any duration you want.

Things to keep in mind

You cannot get leverage when using Longterm (CNC)

Your positions will not be automatically squared off

You cannot take short positions using Longterm (CNC)

You can sell stocks from your holdings when using this product type

When you buy and sell a share on the same day using Longterm (CNC), your trade will still be treated as an intraday trade, and you will be charged brokerage accordingly.

Intraday (MIS - Margin Intraday Square Off)

Intraday (MIS) is used to get intraday leverage for your trades. This product type works for equity, equity F&O, commodity futures, and currency futures.

Things to keep in mind

Overnight (NRML - Normal)

Overnight (NRML) is used for overnight trading of Futures and Options (F&O). This product type allows you to carry your positions until expiry in the derivatives market.

Things to keep in mind

You can hold positions until expiry

You do not get intraday leverage with Overnight (NRML)

You can also use Overnight (NRML) for delivery-based trading of currency