CS50's Introduction to Cybersecurity

David Malan frames security as a trade-off of risk, cost and usability rather than absolutes, walking through the common attacks — phishing, brute force, SQL injection, ransomware — and the everyday defenses like multi-factor auth, password managers and encryption. It needs no prior experience.

It does not make you a security engineer or prepare you for a SOC job — it is awareness and fundamentals, so for hands-on, job-focused training look to a deeper, lab-heavy programme. It is free to audit, with an optional HarvardX certificate. The CS50 team keeps it updated.

CS50's Introduction to Cybersecurity teaches you to protect your own data, devices and systems — and to recognise tomorrow's threats too — at home and at work. Over five self-paced weeks, David Malan covers the threat landscape (phishing and social engineering, brute-force and dictionary attacks, SQL injection, DDoS, viruses, worms and ransomware) and the defenses (multi-factor authentication, password managers, encryption, hashing and salting, firewalls, secure deletion) — framing security as a trade-off of risks, costs and usability rather than absolutes.