OSINT (open-source intelligence) is not a single topic. It is, in short, open-source intelligence. OSINT is as old as the internet and goes by many names including intelligence gathering (IG), information gathering (IG).

The same techniques have been used by network administrators to monitor network traffic and detect intrusions, by social media analysts to monitor hashtags and topics on Twitter, in the military to monitor potential adversaries, and in marketing to monitor competitors.

In this course we'll focus on web servers. You will learn how to find hidden directories and files on any web server or website. You'll learn how to get access to older versions of a website, about web technologies, how to view HTTP headers and how to do automated scans.

Hackers will do content discovery as part of their hacking process, if they find a web server is running. From there, they may find out ways to exploit the scripts (php, node), find documents and more.

This is a beginners course, you don't need any prior knowledge. But, you should have Kali Linux at hands. Kali Linux is a free system designed for Cyber Security and Ethical Hacking, it has around 600 hacking programs. The easiest way to start it is from a USB disk or inside Virtual Box.