A virus is a biological entity that can self-replicate.
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 cellular machinery.
A virus is made up of a protein capsid that surrounds the nucleic acid ( DNA or RNA ). This structure, for its part, can be surrounded by the viral envelope (a lipid layer with different proteins).
Classification of viruses
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 the nucleus of the cell in question as the stage of their development. Within this category there are also two classes: single-stranded, in which single-stranded DNA takes center stage, and double-stranded, which in its case has double-stranded DNA.
On the other hand, we find RNA viruses , which are called that 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 retrotranscribed single-stranded, the double-stranded and the negative single-stranded.
The life cycle of the virus, a potentially pathogenic agent, requires the metabolic machinery of the invaded cell, in order to replicate its genetic material and produce many copies of the original virus. This process can harm the cell until it is destroyed.
The global spread of a virus can cause a pandemic .
The term in computing
This operation has been imitated by so-called computer viruses , which are programs that copy themselves automatically and whose objective is to affect the normal functioning of a computer , without the user's consent.
In the strict sense of the term, computer viruses are programs that can replicate and execute themselves. In their actions, they usually replace system executable files with others infected with 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.
Types of computer viruses
When talking about computer viruses we have to name the most famous or most frequent ones, among which we would find, for example, Trojans . These are those 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 ones known as 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 virus classes. On the one hand, there are viruses that infect files: these, in turn, are divided into direct-action viruses (the infection occurs at the moment they are executed) and resident viruses (they stay in the computer's memory). and infect the rest of the programs as they are accessed). On the other hand, boot or boot sector viruses appear.