Virus is a word of Latin origin, whose meaning is poison or toxin. It is a biological entity that has the ability to self-replicate by using the cellular machinery.

VirusA virus is made up of a protein capsid that surrounds the nucleic acid (DNA or RNA). This structure, for its part, may be surrounded by the viral envelope (a lipid layer with different proteins).

Specifically, we can establish that when classifying viruses we can make two large groups. Thus, on the one hand we would have the so-called DNA viruses that are identified by the fact that they take as the stage of their development what is the nucleus of the cell in question. Within this category there are in turn two classes: the single-stranded, in which a single-stranded DNA takes center stage, and the double-stranded, which in its case has double-stranded DNA.

On the other hand, we find RNA viruses, which are so called because they use RNA (ribonucleic acid) as genetic material and because they also take the cytoplasm as a place to proceed with replication. Within this modality there are four groups: the positive single-stranded, the reverse transcribed single-stranded, the double-stranded and the negative single-stranded.

The life cycle of the virus, a potentially pathogen, requires the metabolic machinery of the invaded cell, in order to be able to replicate its genetic material and produce many copies of the original virus. This process can damage the cell to the point of destroying it.

This operation has been imitated by the so-called computer viruses, What are they programs that are copied automatically and that their objective is to affect the normal operation of a computer, without the consent of the user.

In the strict sense of the term, computer viruses are programs that can replicate and run on their own. In their actions, they usually replace executable files of the system by others infected with the malicious code. Viruses can simply annoy the user, block networks by generating useless traffic, or directly destroy data stored on the computer’s hard drive.

When it comes to talking about computer viruses, we have to name the most famous or most frequent among which, for example, Trojans. These are the ones that can be defined as those that steal information, allow an external user to control the computer or simply alter the aforementioned device.

However, we must also talk about those known as worms whose main hallmark is that they hide and reproduce by themselves. And all this without forgetting the so-called time bombs, which are those viruses that are activated on the date that has been determined or simply when a specific function is performed.

There are two major distinctions between the classes of viruses. On the one hand, there are viruses that infect files: these, in turn, are divided into direct acting virus (the infection occurs the moment they are run) and resident virus (They lodge in the memory of the computer and infect other programs as they are accessed). On the other hand, the boot virus or boot sector.