Final answer:
The three key folders for a Sitecore application's content folder are the Website, Data, and Databases folders. These folders are crucial for the application's operation and include the website files, operational data, and sometimes the databases themselves.
Step-by-step explanation:
The three folders in the physical path of the content folder that hosts the Sitecore application are typically the Website, Data, and Databases folders.
The Website folder contains the actual website files, such as HTML, CSS, JavaScript, and configuration files. The Data folder holds items like logs, indexes, and serialized items that Sitecore uses for its operations. Lastly, the Databases folder includes the databases for the Sitecore application if they are placed within the application structure, though typically databases are hosted separately in a database server like SQL Server.
It's essential to have these folders correctly set up and securely managed, as they are integral to the stability and security of the Sitecore content management system.