Biological weapons are harmful agents, such as bacteria, viruses, or toxins, used intentionally to cause illness or death in humans, animals, or plants. These weapons can be spread through various means, including air, water, or food, making them particularly dangerous and difficult to control. The use of biological weapons is prohibited under international law, specifically the Biological Weapons Convention. Despite this, some countries and groups may still pursue these weapons for military or terrorist purposes, raising concerns about global security and public health.