Final answer:
Computer viruses are typically contracted by opening infected email attachments, downloading compromised files, or using infected hardware. Proper cyber hygiene and the use of antivirus software are crucial for protection against these threats.
Step-by-step explanation:
Computer viruses may be contracted through several means, such as opening infected email attachments. This mode of transmission occurs when a user opens an attachment that contains malicious code, which can then infect their system. Other common ways to get a virus include downloading questionable software or media files from the internet, using infected USB drives, and visiting compromised websites.
While hardware upgrades do not typically transmit viruses unless the hardware itself has been tampered with or contains compromised firmware, cleaning computer screens and typing too fast on the keyboard are not associated with virus infections at all. It's crucial to maintain good cyber hygiene, such as keeping your operating system and antivirus software up to date, to protect against threats.