1. Viruses are a kind of biological puzzle to biologists since they are at the threshold of living and non-living things showing the characteristics of both.
2. They are very much used as biological research tools due to their simplicity of structure and rapid multiplication. They are widely used in research especially in the field of molecular biology, genetic engineering, medicine etc.
3.They are used in eradicating harmful pests like insects. Thus they are used in Biological Control Programmes.
4. Plant viruses cause great concern to agriculturists by their pathogenic nature. Bacteriophages attack the N2 fixing bacteria of soil and are responsible for reducing the fertility of soil.
5. In industry, viruses are used in preparation of sera and vaccines.