Plant viruses are microscopic infectious agents that specifically infect plants. They are made up of genetic material, either DNA or RNA, surrounded by a protein coat. These viruses can spread through various means, including insects, contaminated tools, or even water. Once inside a plant, they hijack the plant's cellular machinery to replicate and spread, often leading to disease. Infected plants may show symptoms such as yellowing leaves, stunted growth, or unusual spots. Some common plant viruses include Tobacco Mosaic Virus and Potato Virus Y. Managing plant viruses often involves using resistant plant varieties, practicing good sanitation, and controlling insect vectors.