A computer virus is a program or software that is loaded onto a computer without user's knowledge and runs itself by adjusting other PC programs and embedding its own particular code. Infected PC projects can incorporate, also, information documents, or the "boot" area of the hard drive. At the point when this replication the affected areas are then said to succeed, the "infected" with computer viruses. All are man-made. An infection works by embeddings or connecting itself to legitimate program or record that backings macros with a specific end goal to execute its code. Simultaneously, an infection can possibly cause surprising or harming impacts, for example, harming the system software by corrupting or destroying data. At the point when the infection is executed, it spreads by duplicating itself into or over information documents, projects, or boot division of a PC's hard drive, or possibly whatever else writable. To help spread a disease the infection scholars use detailed knowledge of security vulnerabilities.it is dangerous because it will quickly use all available memory and bring the memory and convey the framework to an end. A much more hazardous kind of infection is one fit for transmitting itself across systems and bypassing security frameworks. Since 1987, when a virus infected ARPANET, a large network used by the Defense Department and many universities, many antiviruses software have become available. These programs periodically check your PC framework for the best-known sorts of infections.
Types of Computer viruses
1. Compiled Viruses- A compiled virus that has had its source code converted by a compiler program into a format that can be directly executed by an operating system.
compiled viruses commonly divided into three categories
- File Infector
- Boot sector
2. Interpreted Viruses- These are the more prevalent type of virus. An interpreted virus is composed of program or code which can be executed only by a particular application or service. These are comparatively easy to generate. A relatively unskilled attacker can acquire an interpreted virus, review and modify its source code, and distribute it to others. There are often dozens of variants of a single interpreted virus, most with only trivial changes from the original.
Interpreted Viruses commonly divided into two categories
- macro viruses
- scripting viruses