On the surface, websites look like they’re designed to make information available to the public. However, there is plenty of valuable information hiding behind what you are able to see in your web browser.
A website and its elements
- Website and webpage
- IP address
- Domain name
- Domain registrar, domain registrants & domain registration
- Web host
- Basic WHOIS Look-up
- GDPR implications
- Historic WHOIS
- Reverse WHOIS Look-up
- Finding information with shared hosting and reverse IP search
- Discovering useful information in a webpage’s source code
- Finding connections with reverse Google Analytics ID
- How can these searches help an investigation?
- Metadata analysis
- Exposing Hidden Web Content
- Robots.txt
- Sitemap.xml
- Subdomain enumeration
- Resources
- Articles and Guides
- Tools and Databases
- Glossary
Very long & good read, one must have a look! 
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