# Some Basics

* A **vulnerability is a weakness which can be exploited** by an attacker.\\

* An **exploit is a piece of code written to take advantage of a particular vulnerability**.\\

* A **payload is a piece of code to be executed** through said exploit.\\

* The **Common Vulnerabilities and Exposures (CVE) system** provides a reference-method for **publicly known information-security vulnerabilities and exposures**.\\

* **Nessus is a proprietary vulnerability scanner** developed by Tenable, Inc.\\

* Layer 7 refers to the **top layer in the 7-layer OSI model** of the Internet, also known as the **"application layer."**\\

* The **HTTP requests and responses used to load webpages**, for example, are layer 7 events.
