Pests and diseases are harmful organisms that can negatively affect plants, animals, and humans. Pests include insects, rodents, and weeds that compete for resources or damage crops. Common examples are aphids, cockroaches, and dandelions. Diseases are caused by pathogens like bacteria, viruses, and fungi, leading to health issues in plants and animals. Managing pests and diseases is crucial for agriculture and public health. Farmers often use methods like integrated pest management (IPM) to control pests while minimizing harm to the environment. Similarly, vaccines and treatments are developed to combat diseases in both humans and animals, ensuring healthier populations.