Which permission type is needed to open files and view folder content?

The permission type needed to open files and view folder content is Read. This permission allows a user to view the contents of a file or directory without the ability to modify or delete it. When a user has Read permission, they can open and access the file to see its contents, or navigate through a folder to see its items, but they cannot make any changes to those files or folders.

In the context of file and folder permissions, read access is fundamental for users who need to review or assess the data without the risk of altering it. Other permission types, such as Full Control and Modify, include capabilities that extend beyond merely viewing, which may not be necessary if the user only needs to observe the content. Write permission, on the other hand, allows for changes to be made, which is not required for merely opening or viewing files. This makes Read the appropriate choice for this scenario.