## What is Cybersecurity?

**Cybersecurity** is the practice of protecting systems, networks, and programs from digital attacks. These cyberattacks are usually aimed at accessing, changing, or destroying sensitive information; extorting money from users; or interrupting normal business processes.

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### The Evolution of Hacking
To understand where we are, we must look at where we came from.

#### 1. The Era of Phreaking (1970s)
Before computers were networked, hackers targeted **phones**. "Phreakers" like John Draper (Captain Crunch) used a toy whistle that emitted a 2600Hz tone. This tone tricked the AT&T phone switches into giving free long-distance calls.
*   **Motivation**: Curiosity.

#### 2. The Morris Worm (1988)
Robert Morris wrote a script to gauge the size of the internet. A coding error made it propagate uncontrollably. It crashed 10% of the entire internet.
*   **Impact**: The first conviction under the Computer Fraud and Abuse Act.

#### 3. The Script Kiddie Era (1990s-2000s)
Tools became public. You didn't need to know C code; you just needed to download "Sub7" or "Back Orifice". Defacements of websites were common.
*   **Motivation**: Fame / Notoriety.

#### 4. The Era of Cybercrime (2010s-Present)
Hacking became a business. Organized crime groups (like Conti, LockBit) run "Ransomware as a Service". They have HR departments, helpdesks, and payroll.
*   **Motivation**: Money. Trillions of dollars lost annually.

#### 5. Cyber Warfare (State Sponsored)
Nations (US, China, Russia, Israel, Iran) use cyber tools for espionage and sabotage.
*   **Stuxnet (2010)**: A worm that physically destroyed Iranian nuclear centrifuges. The first "digital weapon".

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### Why is Cybersecurity Hard?
1.  **The Defender's Dilemma**: A defender must be right 100% of the time. An attacker only needs to be right ONCE.
2.  **Complexity**: Modern software has millions of lines of code. Bugs are inevitable.
3.  **The Human Factor**: You can have a $1 Million Firewall, but if Dave in Accounting clicks a link that says "Free iPhone", you are breached.

### Key Terminology
*   **Threat**: The potential cause of an unwanted incident (e.g., A hacker, a hurricane).
*   **Vulnerability**: A weakness in a system (e.g., Weak password, unpatched Windows).
*   **Risk**: The likelihood of a Threat exploiting a Vulnerability. (`Risk = Threat x Vulnerability`).