How are viruses different from other microorganisms, and what is their mode of reproduction?

Viruses differ from other microorganisms in that they lack cellular structures and cannot carry out metabolic processes independently. They reproduce only inside host cells, which may be bacteria, plants, or animals.
Unlike bacteria, fungi, protozoa, and algae, viruses do not have a cellular structure or the machinery for independent life functions. Instead, they inject their genetic material into host cells, taking over the cellular machinery to replicate and produce more viruses. This obligate parasitism distinguishes viruses, causing ailments like the common cold, influenza, and more severe diseases such as polio and chickenpox.