Second-degree murder is a type of homicide that involves the intentional killing of another person, but without premeditation or planning. This means that the act was not thought out in advance, but the person still acted with a disregard for human life. It often occurs in the heat of the moment, such as during an argument or confrontation. In many jurisdictions, second-degree murder carries serious penalties, typically less severe than first-degree murder, which involves premeditation. The legal definitions and consequences can vary by state or country, but it generally reflects a significant level of culpability and intent to cause harm.