Aggression is any behavior, including verbal events, which involves attacking another person, animal, or object with the intent of harming the target. It can be channeled into creative and practical outlets for some, but it is often hostile and antagonistic behavior, often with the intent to cause harm. Aggression can be classified into different types based on the context and intent, such as:

• Reactive aggression: This is a response to a perceived threat or provocation, such as hitting someone in response to an insult.
• Proactive aggression: This is a premeditated and calculated behavior aimed at achieving a goal, such as bullying or manipulating others.
• Emotional aggression: This is the result of extreme negative emotions, such as anger, frustration, or jealousy, and is not intended to create any positive outcomes.
• Instrumental aggression: This is a calculated behavior aimed at achieving a specific goal, such as winning a competition or gaining resources.

Aggression can have biological, psychological, and socioeconomic causes. Biological causes include genetics, medical and psychiatric diseases, neurotransmitters, hormones, substances of abuse, and medications. Psychological causes include numerous DSM–5 diagnoses, such as bipolar affective disorder, schizophrenia, major depression, general anxiety disorder, and antisocial personality. Socioeconomic causes include exposure to violence and aggression during upbringing, poverty, and social inequality.

It is important to note that aggression and violence are often used interchangeably, but they are two different things. Violence is intentionally using physical force to hurt, damage, or kill someone or something, while aggression can be verbal or non-physical.