A bear call spread is an options strategy used by traders looking to profit from a decrease in the price of a security. Traders using this strategy will purchase a call option at a specific strike price, while also selling a call option at a higher strike price. This type of spread is categorized as a vertical spread as the two options involved have the same expiration date, but different strike prices.

This kind of spread is considered to be a "limited-risk, limited-profit" trading strategy as traders know that potential loss can never exceed the net premium they paid while setting up the spread. On the other hand, their potential profit is limited to the difference in strike prices less the net premium they paid.

In order to set up a bear call spread, the trader must first purchase a call option with a strike price at or above the current price of the asset. This call option purchased is known as the long position. They must also sell a call option with a higher strike price. The call option sold is referred to as the short position. The net premium paid for the spread is the difference between the price of the long position and the short position.

The goal of a bear call spread is to profit if the underlying asset’s price falls in such a way that both the long and short options expire worthless or out of the money. If the security's price goes down and the short option expires worthless, the trader’s position will have a profit which is equal to the net premium received for the spread. The maximum profit for this kind of spread is realized when the underlying asset’s price is at or below the strike price of the option purchased.

On the other hand, if the security's price increases, the trader’s maximum loss will be equal to the net premium paid for setting up the spread. The maximum loss for this kind of spread is realized when the price of the underlying asset is at or above the strike price of the option sold.

Overall, bear call spreads are considered to be a great risk-averse strategy for traders looking to benefit from a decrease in the price of an asset. They are able to contain the losses by knowing their maximum potential profit and loss in advance. It can also be employed when expectations are neutral; if the security's price stays within the spread’s strike prices, the spread will expire and the trader will be able to keep the net premium paid.