A more thorough explanation:

Lethal injection is a method of carrying out the death penalty by injecting a deadly substance into a prisoner's body. This is done to end the prisoner's life as a form of punishment for a serious crime they have committed.

For example, in some states in the United States, lethal injection is the primary method of execution for prisoners on death row. The prisoner is strapped to a gurney and a series of drugs are injected into their body, causing them to lose consciousness and eventually stop breathing.

Another example is the use of lethal injection in other countries such as China, Thailand, and Vietnam. These countries also use lethal injection as a form of capital punishment.

The use of lethal injection as a method of execution is controversial and has been the subject of much debate. Some argue that it is a more humane method of execution compared to other methods such as hanging or electrocution, while others argue that it is still a cruel and inhumane form of punishment.