The first PC virus was developed in 1986.

Explanation:

The development of the first PC virus marks a significant milestone in the history of cybersecurity. It paved the way for the emergence of various malicious software and prompted the need for antivirus protection.

1. Background:
- In the early 1980s, personal computers were gaining popularity, and the internet was starting to connect computers globally.
- As computer networks expanded, so did the opportunities for hackers and programmers to exploit vulnerabilities and gain unauthorized access to systems.

2. Emergence of the First PC Virus:
- In 1986, two Pakistani brothers, Basit and Amjad Farooq Alvi, created the first PC virus known as "Brain."
- The brothers developed this virus as a means to protect their medical software from unauthorized copying.
- The Brain virus was spread through infected floppy disks, which were commonly used for data storage at the time.

3. Characteristics of the Brain Virus:
- The Brain virus infected the boot sector of the disk, making it difficult to detect and remove.
- Once a computer was infected, the virus would slow down the system and display a message containing the contact information of the Alvi brothers.
- The primary purpose of the Brain virus was not to cause harm but to prevent unauthorized use of their software.

4. Impact and Legacy:
- While the Brain virus did not cause extensive damage, it served as a wake-up call for the cybersecurity community.
- It highlighted the vulnerabilities of computer systems and the need for protective measures against malware.
- The development of the Brain virus paved the way for the emergence of more sophisticated and malicious viruses, worms, and other types of malware.

In conclusion, the first PC virus, known as the Brain virus, was developed in 1986 by Basit and Amjad Farooq Alvi. Although it was created with a benign intention, it marked a turning point in the development and proliferation of malware. The Brain virus brought attention to the vulnerabilities of computer systems and the importance of implementing cybersecurity measures.