: This searches for the text file extension. In many cases, these files are simple logs or database dumps that were accidentally left in a public directory (like /uploads/ or /backups/ ).
Each part of this "dork" serves a filter function to narrow down millions of web pages into a specific set of potentially sensitive files: -gmail.com -yahoo.com -hotmail.com -aol.com txt 2021
This particular query is designed to find from the year 2021, while specifically excluding the most common consumer email providers (Gmail, Yahoo, Hotmail, and AOL). Understanding the Dork: Breakdown of the Syntax : This searches for the text file extension