Computer Viruses
Computer viruses are malicious software programs designed to infect a computer system and cause harm to the data and functionality of the system. They are usually spread through infected files or links and can replicate themselves within a system, spreading to other files and devices connected to the infected system. Here is a detailed explanation of computer viruses:

Types of Computer Viruses:
- File Infector Virus: Attaches itself to executable files and spreads when the infected file is executed.
- Boot Sector Virus: Infects the boot sector of a storage device and activates when the system is booted.
- Macro Virus: Spreads through macro programming code in documents and spreads when the document is opened.
- Polymorphic Virus: Changes its code to avoid detection by antivirus software.
- Resident Virus: Lodges itself in the system's memory and can infect files as they are accessed.

Effects of Computer Viruses:
- Data Loss: Viruses can corrupt or delete files, leading to loss of important data.
- System Slowdown: Viruses consume system resources, leading to a slowdown in performance.
- Unauthorized Access: Some viruses can open backdoors in a system, allowing hackers to access sensitive information.
- System Crashes: Viruses can cause the system to crash or freeze, making it unusable.

Prevention and Removal:
- Use Antivirus Software: Install and regularly update antivirus software to detect and remove viruses.
- Be cautious online: Avoid downloading files from untrusted sources and clicking on suspicious links.
- Keep software updated: Update operating systems and software programs to patch security vulnerabilities.
- Backup data: Regularly backup important data to prevent loss in case of a virus attack.
In conclusion, computer viruses are a serious threat to the security and functionality of computer systems. It is important to take preventive measures to protect against viruses and regularly scan and clean infected systems to minimize damage.