A debit spread, involves buying an option with a higher premium and simultaneously selling an option with a lower premium, where the premium paid for the long option of the spread is greater than the premium received from the written option.
When a debit spread is used, a premium is deducted from the trader's or investor's account at the time the position is opened, as opposed to a credit spread. To reduce the costs of holding long options positions, traders use debit spreads.

A debit spread is an options trading strategy where an investor simultaneously buys and sells options of the same class (calls or puts) on the same underlying asset, but with different strike prices or expiration dates. The strategy results in a net cost, or debit, hence the name "debit spread."

There are two main types of debit spreads: bull call spreads and bear put spreads. In a bull call spread, the investor buys a call option with a lower strike price and sells one with a higher strike price. In a bear put spread, the investor buys a put option with a higher strike price and sells one with a lower strike price.

Debit spreads limit potential profit but also reduce risk, making them a popular strategy in options trading.